Index: lemon/CMakeLists.txt
===================================================================
--- lemon/CMakeLists.txt	(revision 458)
+++ lemon/CMakeLists.txt	(revision 459)
@@ -5,7 +5,4 @@
   base.cc
   color.cc
-  lp_base.cc
-  lp_skeleton.cc
-  lp_utils.cc
   random.cc)
 
Index: lemon/Makefile.am
===================================================================
--- lemon/Makefile.am	(revision 458)
+++ lemon/Makefile.am	(revision 459)
@@ -19,21 +19,27 @@
 	$(GLPK_CFLAGS) \
 	$(CPLEX_CFLAGS) \
-	$(SOPLEX_CXXFLAGS)
+	$(SOPLEX_CXXFLAGS) \
+	$(CLP_CXXFLAGS)
 
 lemon_libemon_la_LDFLAGS = \
 	$(GLPK_LIBS) \
 	$(CPLEX_LIBS) \
-	$(SOPLEX_LIBS)
+	$(SOPLEX_LIBS) \
+	$(CLP_LIBS)
 
 if HAVE_GLPK
-lemon_libemon_la_SOURCES += lemon/lp_glpk.cc lemon/mip_glpk.cc
+lemon_libemon_la_SOURCES += lemon/lp_glpk.cc
 endif
 
 if HAVE_CPLEX
-lemon_libemon_la_SOURCES += lemon/lp_cplex.cc lemon/mip_cplex.cc
+lemon_libemon_la_SOURCES += lemon/lp_cplex.cc
 endif
 
 if HAVE_SOPLEX
 lemon_libemon_la_SOURCES += lemon/lp_soplex.cc
+endif
+
+if HAVE_CLP
+lemon_libemon_la_SOURCES += lemon/lp_clp.cc
 endif
 
@@ -66,10 +72,10 @@
 	lemon/lp.h \
 	lemon/lp_base.h \
+	lemon/lp_clp.h \
 	lemon/lp_cplex.h \
 	lemon/lp_glpk.h \
 	lemon/lp_skeleton.h \
 	lemon/lp_soplex.h \
-	lemon/mip_cplex.h \
-	lemon/mip_glpk.h \
+	lemon/list_graph.h \
 	lemon/maps.h \
 	lemon/math.h \
@@ -95,7 +101,7 @@
 	lemon/bits/graph_adaptor_extender.h \
 	lemon/bits/graph_extender.h \
-	lemon/bits/lp_id.h \
 	lemon/bits/map_extender.h \
 	lemon/bits/path_dump.h \
+	lemon/bits/solver_bits.h \
 	lemon/bits/traits.h \
 	lemon/bits/variant.h \
Index: lemon/bits/lp_id.h
===================================================================
--- lemon/bits/lp_id.h	(revision 458)
+++ 	(revision )
@@ -1,157 +1,0 @@
-/* -*- mode: C++; indent-tabs-mode: nil; -*-
- *
- * This file is a part of LEMON, a generic C++ optimization library.
- *
- * Copyright (C) 2003-2008
- * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
- * (Egervary Research Group on Combinatorial Optimization, EGRES).
- *
- * Permission to use, modify and distribute this software is granted
- * provided that this copyright notice appears in all copies. For
- * precise terms see the accompanying LICENSE file.
- *
- * This software is provided "AS IS" with no warranty of any kind,
- * express or implied, and with no claim as to its suitability for any
- * purpose.
- *
- */
-
-#ifndef LEMON_BITS_LP_SOLVER_ID_H
-#define LEMON_BITS_LP_SOLVER_ID_H
-
-namespace lemon {
-
-  namespace _lp_bits {
-
-    struct LpIdImpl {
-      std::vector<int> index;
-      std::vector<int> cross;
-      int first_index;
-      int first_free;
-    };
-
-    class LpId {
-    public:
-
-      class IdHandler {
-      public:
-        virtual ~IdHandler() {}
-        virtual int addId(LpIdImpl&) = 0;
-        virtual void eraseId(LpIdImpl&, int xn) = 0;
-      };
-
-      LpId(int min_index = 0) {
-        id_handler = 0;
-        impl.first_free = -1;
-        impl.first_index = min_index;
-        impl.cross.resize(impl.first_index);
-      }
-
-      LpId(const LpId& li) {
-        id_handler = 0;
-        impl = li.impl;
-      }
-
-      LpId& operator=(const LpId& li) {
-        id_handler = 0;
-        impl = li.impl;
-        return *this;
-      }
-
-      void setIdHandler(IdHandler& ih) {
-        id_handler = &ih;
-      }
-
-      int fixId(int fn) const {return impl.cross[fn];}
-      int floatingId(int xn) const {return impl.index[xn];}
-
-      int addId() {
-        if (id_handler == 0) {
-          int xn, fn = impl.cross.size();
-          if (impl.first_free == -1) {
-            xn = impl.index.size();
-            impl.index.push_back(fn);
-          } else {
-            xn = impl.first_free;
-            impl.first_free = impl.index[impl.first_free];
-            impl.index[xn] = fn;
-          }
-          impl.cross.push_back(xn);
-          return xn;
-        } else {
-          return id_handler->addId(impl);
-        }
-      }
-
-      void eraseId(int xn) {
-        if (id_handler == 0) {
-          int fn = impl.index[xn];
-          impl.index[xn] = impl.first_free;
-          impl.first_free = xn;
-          for(int i = fn + 1; i < int(impl.cross.size()); ++i) {
-            impl.cross[i - 1] = impl.cross[i];
-            impl.index[impl.cross[i]]--;
-          }
-          impl.cross.pop_back();
-        } else {
-          id_handler->eraseId(impl, xn);
-        }
-      }
-
-      void firstFloating(int& fn) const {
-        fn = impl.first_index;
-        if (fn == int(impl.cross.size())) fn = -1;
-      }
-
-      void nextFloating(int& fn) const {
-        ++fn;
-        if (fn == int(impl.cross.size())) fn = -1;
-      }
-
-      void firstFix(int& xn) const {
-        int fn;
-        firstFloating(fn);
-        xn = fn != -1 ? fixId(fn) : -1;
-      }
-
-      void nextFix(int& xn) const {
-        int fn = floatingId(xn);
-        nextFloating(fn);
-        xn = fn != -1 ? fixId(fn) : -1;
-      }
-
-    protected:
-      LpIdImpl impl;
-      IdHandler *id_handler;
-    };
-
-    class RelocateIdHandler : public LpId::IdHandler {
-    public:
-
-      virtual int addId(LpIdImpl& impl) {
-        int xn, fn = impl.cross.size();
-        if (impl.first_free == -1) {
-          xn = impl.index.size();
-          impl.index.push_back(fn);
-        } else {
-          xn = impl.first_free;
-          impl.first_free = impl.index[impl.first_free];
-          impl.index[xn] = fn;
-        }
-        impl.cross.push_back(xn);
-        return xn;
-      }
-
-      virtual void eraseId(LpIdImpl& impl, int xn) {
-        int fn = impl.index[xn];
-        impl.index[xn] = impl.first_free;
-        impl.first_free = xn;
-        impl.cross[fn] = impl.cross.back();
-        impl.index[impl.cross.back()] = fn;
-        impl.cross.pop_back();
-      }
-    };
-  }
-}
-
-#endif
Index: lemon/bits/solver_bits.h
===================================================================
--- lemon/bits/solver_bits.h	(revision 459)
+++ lemon/bits/solver_bits.h	(revision 459)
@@ -0,0 +1,191 @@
+/* -*- mode: C++; indent-tabs-mode: nil; -*-
+ *
+ * This file is a part of LEMON, a generic C++ optimization library.
+ *
+ * Copyright (C) 2003-2008
+ * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
+ * (Egervary Research Group on Combinatorial Optimization, EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ */
+
+#ifndef LEMON_BITS_SOLVER_BITS_H
+#define LEMON_BITS_SOLVER_BITS_H
+
+namespace lemon {
+
+  namespace _solver_bits {
+
+    class VarIndex {
+    private:
+      struct ItemT {
+        int prev, next;
+        int index;
+      };
+      std::vector<ItemT> items;
+      int first_item, last_item, first_free_item;
+
+      std::vector<int> cross;
+
+    public:
+
+      VarIndex()
+        : first_item(-1), last_item(-1), first_free_item(-1) {
+      }
+
+      void clear() {
+        first_item = -1;
+        first_free_item = -1;
+        items.clear();
+        cross.clear();
+      }
+
+      int addIndex(int idx) {
+        int n;
+        if (first_free_item == -1) {
+          n = items.size();
+          items.push_back(ItemT());
+        } else {
+          n = first_free_item;
+          first_free_item = items[n].next;
+          if (first_free_item != -1) {
+            items[first_free_item].prev = -1;
+          }
+        }
+        items[n].index = idx;
+        if (static_cast<int>(cross.size()) <= idx) {
+          cross.resize(idx + 1, -1);
+        }
+        cross[idx] = n;
+
+        items[n].prev = last_item;
+        items[n].next = -1;
+        if (last_item != -1) {
+          items[last_item].next = n;
+        } else {
+          first_item = n;
+        }
+        last_item = n;
+
+        return n;
+      }
+
+      int addIndex(int idx, int n) {
+        while (n >= static_cast<int>(items.size())) {
+          items.push_back(ItemT());
+          items.back().prev = -1;
+          items.back().next = first_free_item;
+          if (first_free_item != -1) {
+            items[first_free_item].prev = items.size() - 1;
+          }
+          first_free_item = items.size() - 1;
+        }
+        if (items[n].next != -1) {
+          items[items[n].next].prev = items[n].prev;
+        }
+        if (items[n].prev != -1) {
+          items[items[n].prev].next = items[n].next;
+        } else {
+          first_free_item = items[n].next;
+        }
+
+        items[n].index = idx;
+        if (static_cast<int>(cross.size()) <= idx) {
+          cross.resize(idx + 1, -1);
+        }
+        cross[idx] = n;
+
+        items[n].prev = last_item;
+        items[n].next = -1;
+        if (last_item != -1) {
+          items[last_item].next = n;
+        } else {
+          first_item = n;
+        }
+        last_item = n;
+
+        return n;
+      }
+
+      void eraseIndex(int idx) {
+        int n = cross[idx];
+
+        if (items[n].prev != -1) {
+          items[items[n].prev].next = items[n].next;
+        } else {
+          first_item = items[n].next;
+        }
+        if (items[n].next != -1) {
+          items[items[n].next].prev = items[n].prev;
+        } else {
+          last_item = items[n].prev;
+        }
+
+        if (first_free_item != -1) {
+          items[first_free_item].prev = n;
+        }
+        items[n].next = first_free_item;
+        items[n].prev = -1;
+        first_free_item = n;
+
+        while (!cross.empty() && cross.back() == -1) {
+          cross.pop_back();
+        }
+      }
+
+      int maxIndex() const {
+        return cross.size() - 1;
+      }
+
+      void shiftIndices(int idx) {
+        for (int i = idx + 1; i < static_cast<int>(cross.size()); ++i) {
+          cross[i - 1] = cross[i];
+          if (cross[i] != -1) {
+            --items[cross[i]].index;
+          }
+        }
+        cross.back() = -1;
+        cross.pop_back();
+        while (!cross.empty() && cross.back() == -1) {
+          cross.pop_back();
+        }
+      }
+
+      void relocateIndex(int idx, int jdx) {
+        cross[idx] = cross[jdx];
+        items[cross[jdx]].index = idx;
+        cross[jdx] = -1;
+
+        while (!cross.empty() && cross.back() == -1) {
+          cross.pop_back();
+        }
+      }
+
+      int operator[](int idx) const {
+        return cross[idx];
+      }
+
+      int operator()(int fdx) const {
+        return items[fdx].index;
+      }
+
+      void firstItem(int& fdx) const {
+        fdx = first_item;
+      }
+
+      void nextItem(int& fdx) const {
+        fdx = items[fdx].next;
+      }
+
+    };
+  }
+}
+
+#endif
Index: lemon/config.h.in
===================================================================
--- lemon/config.h.in	(revision 458)
+++ lemon/config.h.in	(revision 459)
@@ -13,2 +13,5 @@
 /* Define to 1 if you have SOPLEX */
 #undef HAVE_SOPLEX
+
+/* Define to 1 if you have CLP */
+#undef HAVE_CLP
Index: lemon/lp.h
===================================================================
--- lemon/lp.h	(revision 458)
+++ lemon/lp.h	(revision 459)
@@ -25,10 +25,10 @@
 #ifdef HAVE_GLPK
 #include <lemon/lp_glpk.h>
-#include <lemon/mip_glpk.h>
 #elif HAVE_CPLEX
 #include <lemon/lp_cplex.h>
-#include <lemon/mip_cplex.h>
 #elif HAVE_SOPLEX
 #include <lemon/lp_soplex.h>
+#elif HAVE_CLP
+#include <lemon/lp_clp.h>
 #endif
 
@@ -44,6 +44,7 @@
   ///\ingroup lp_group
   ///
-  ///Currently, the possible values are \c GLPK or \c CPLEX
-#define DEFAULT_LP SOLVER
+  ///Currently, the possible values are \c LP_GLPK, \c LP_CPLEX, \c
+  ///LP_SOPLEX or \c LP_CLP
+#define LEMON_DEFAULT_LP SOLVER
   ///The default LP solver
 
@@ -51,36 +52,38 @@
   ///\ingroup lp_group
   ///
-  ///Currently, it is either \c LpGlpk or \c LpCplex
+  ///Currently, it is either \c LpGlpk, \c LpCplex, \c LpSoplex or \c LpClp
   typedef LpGlpk Lp;
-  ///The default LP solver identifier string
 
-  ///The default LP solver identifier string.
+  ///The default MIP solver identifier
+
+  ///The default MIP solver identifier.
   ///\ingroup lp_group
   ///
-  ///Currently, the possible values are "GLPK" or "CPLEX"
-  const char default_solver_name[]="SOLVER";
+  ///Currently, the possible values are \c MIP_GLPK or \c MIP_CPLEX
+#define LEMON_DEFAULT_MIP SOLVER
+  ///The default MIP solver.
 
-  ///The default ILP solver.
-
-  ///The default ILP solver.
+  ///The default MIP solver.
   ///\ingroup lp_group
   ///
-  ///Currently, it is either \c LpGlpk or \c LpCplex
+  ///Currently, it is either \c MipGlpk or \c MipCplex
   typedef MipGlpk Mip;
 #else
 #ifdef HAVE_GLPK
-#define DEFAULT_LP GLPK
+# define LEMON_DEFAULT_LP LP_GLPK
   typedef LpGlpk Lp;
+# define LEMON_DEFAULT_MIP MIP_GLPK
   typedef MipGlpk Mip;
-  const char default_solver_name[]="GLPK";
 #elif HAVE_CPLEX
-#define DEFAULT_LP CPLEX
+# define LEMON_DEFAULT_LP LP_CPLEX
   typedef LpCplex Lp;
+# define LEMON_DEFAULT_MIP MIP_CPLEX
   typedef MipCplex Mip;
-  const char default_solver_name[]="CPLEX";
 #elif HAVE_SOPLEX
-#define DEFAULT_LP SOPLEX
+# define DEFAULT_LP LP_SOPLEX
   typedef LpSoplex Lp;
-  const char default_solver_name[]="SOPLEX";
+#elif HAVE_CLP
+# define DEFAULT_LP LP_CLP
+  typedef LpClp Lp;  
 #endif
 #endif
Index: lemon/lp_base.cc
===================================================================
--- lemon/lp_base.cc	(revision 458)
+++ lemon/lp_base.cc	(revision 459)
@@ -23,13 +23,6 @@
 namespace lemon {
 
-  const LpSolverBase::Value
-  LpSolverBase::INF = std::numeric_limits<Value>::infinity();
-  const LpSolverBase::Value
-  LpSolverBase::NaN = std::numeric_limits<Value>::quiet_NaN();
-
-//   const LpSolverBase::Constr::Value
-//   LpSolverBase::Constr::INF = std::numeric_limits<Value>::infinity();
-//   const LpSolverBase::Constr::Value
-//   LpSolverBase::Constr::NaN = std::numeric_limits<Value>::quiet_NaN();
+  const LpBase::Value LpBase::INF = std::numeric_limits<Value>::infinity();
+  const LpBase::Value LpBase::NaN = std::numeric_limits<Value>::quiet_NaN();
 
 } //namespace lemon
Index: lemon/lp_base.h
===================================================================
--- lemon/lp_base.h	(revision 458)
+++ lemon/lp_base.h	(revision 459)
@@ -26,6 +26,9 @@
 #include<lemon/math.h>
 
+#include<lemon/error.h>
+#include<lemon/assert.h>
+
 #include<lemon/core.h>
-#include<lemon/bits/lp_id.h>
+#include<lemon/bits/solver_bits.h>
 
 ///\file
@@ -34,31 +37,15 @@
 namespace lemon {
 
-  /// Function to decide whether a floating point value is finite or not.
-
-  /// Retruns true if the argument is not infinity, minus infinity or NaN.
-  /// It does the same as the isfinite() function defined by C99.
-  template <typename T>
-  bool isFinite(T value)
-  {
-    typedef std::numeric_limits<T> Lim;
-    if ((Lim::has_infinity && (value == Lim::infinity() || value ==
-                               -Lim::infinity())) ||
-        ((Lim::has_quiet_NaN || Lim::has_signaling_NaN) && value != value))
-    {
-      return false;
-    }
-    return true;
-  }
-
-  ///Common base class for LP solvers
-
-  ///\todo Much more docs
+  ///Common base class for LP and MIP solvers
+
+  ///Usually this class is not used directly, please use one of the concrete
+  ///implementations of the solver interface.
   ///\ingroup lp_group
-  class LpSolverBase {
+  class LpBase {
 
   protected:
 
-    _lp_bits::LpId rows;
-    _lp_bits::LpId cols;
+    _solver_bits::VarIndex rows;
+    _solver_bits::VarIndex cols;
 
   public:
@@ -75,36 +62,10 @@
     };
 
-      ///\e
-    enum SolutionStatus {
-      ///Feasible solution hasn't been found (but may exist).
-
-      ///\todo NOTFOUND might be a better name.
-      ///
-      UNDEFINED = 0,
-      ///The problem has no feasible solution
-      INFEASIBLE = 1,
-      ///Feasible solution found
-      FEASIBLE = 2,
-      ///Optimal solution exists and found
-      OPTIMAL = 3,
-      ///The cost function is unbounded
-
-      ///\todo Give a feasible solution and an infinite ray (and the
-      ///corresponding bases)
-      INFINITE = 4
-    };
-
-    ///\e The type of the investigated LP problem
-    enum ProblemTypes {
-      ///Primal-dual feasible
-      PRIMAL_DUAL_FEASIBLE = 0,
-      ///Primal feasible dual infeasible
-      PRIMAL_FEASIBLE_DUAL_INFEASIBLE = 1,
-      ///Primal infeasible dual feasible
-      PRIMAL_INFEASIBLE_DUAL_FEASIBLE = 2,
-      ///Primal-dual infeasible
-      PRIMAL_DUAL_INFEASIBLE = 3,
-      ///Could not determine so far
-      UNKNOWN = 4
+    ///Direction of the optimization
+    enum Sense {
+      /// Minimization
+      MIN,
+      /// Maximization
+      MAX
     };
 
@@ -116,9 +77,8 @@
     static const Value NaN;
 
-    static inline bool isNaN(const Value& v) { return v!=v; }
-
     friend class Col;
     friend class ColIt;
     friend class Row;
+    friend class RowIt;
 
     ///Refer to a column of the LP.
@@ -129,41 +89,91 @@
     ///other columns.
     ///
-    ///\todo Document what can one do with a Col (INVALID, comparing,
-    ///it is similar to Node/Edge)
+    ///\note This class is similar to other Item types in LEMON, like
+    ///Node and Arc types in digraph.
     class Col {
+      friend class LpBase;
     protected:
-      int id;
-      friend class LpSolverBase;
-      friend class MipSolverBase;
-      explicit Col(int _id) : id(_id) {}
+      int _id;
+      explicit Col(int id) : _id(id) {}
     public:
       typedef Value ExprValue;
-      typedef True LpSolverCol;
+      typedef True LpCol;
+      /// Default constructor
+      
+      /// \warning The default constructor sets the Col to an
+      /// undefined value.
       Col() {}
-      Col(const Invalid&) : id(-1) {}
-      bool operator< (Col c) const  {return id< c.id;}
-      bool operator> (Col c) const  {return id> c.id;}
-      bool operator==(Col c) const  {return id==c.id;}
-      bool operator!=(Col c) const  {return id!=c.id;}
+      /// Invalid constructor \& conversion.
+      
+      /// This constructor initializes the Col to be invalid.
+      /// \sa Invalid for more details.      
+      Col(const Invalid&) : _id(-1) {}
+      /// Equality operator
+
+      /// Two \ref Col "Col"s are equal if and only if they point to
+      /// the same LP column or both are invalid.
+      bool operator==(Col c) const  {return _id == c._id;}
+      /// Inequality operator
+
+      /// \sa operator==(Col c)
+      ///
+      bool operator!=(Col c) const  {return _id != c._id;}
+      /// Artificial ordering operator.
+
+      /// To allow the use of this object in std::map or similar
+      /// associative container we require this.
+      ///
+      /// \note This operator only have to define some strict ordering of
+      /// the items; this order has nothing to do with the iteration
+      /// ordering of the items.
+      bool operator<(Col c) const  {return _id < c._id;}
     };
 
+    ///Iterator for iterate over the columns of an LP problem
+
+    /// Its usage is quite simple, for example you can count the number
+    /// of columns in an LP \c lp:
+    ///\code
+    /// int count=0;
+    /// for (LpBase::ColIt c(lp); c!=INVALID; ++c) ++count;
+    ///\endcode
     class ColIt : public Col {
-      const LpSolverBase *_lp;
+      const LpBase *_solver;
     public:
+      /// Default constructor
+      
+      /// \warning The default constructor sets the iterator
+      /// to an undefined value.
       ColIt() {}
-      ColIt(const LpSolverBase &lp) : _lp(&lp)
+      /// Sets the iterator to the first Col
+      
+      /// Sets the iterator to the first Col.
+      ///
+      ColIt(const LpBase &solver) : _solver(&solver)
       {
-        _lp->cols.firstFix(id);
-      }
+        _solver->cols.firstItem(_id);
+      }
+      /// Invalid constructor \& conversion
+      
+      /// Initialize the iterator to be invalid.
+      /// \sa Invalid for more details.
       ColIt(const Invalid&) : Col(INVALID) {}
+      /// Next column
+      
+      /// Assign the iterator to the next column.
+      ///
       ColIt &operator++()
       {
-        _lp->cols.nextFix(id);
+        _solver->cols.nextItem(_id);
         return *this;
       }
     };
 
-    static int id(const Col& col) { return col.id; }
-
+    /// \brief Returns the ID of the column.
+    static int id(const Col& col) { return col._id; }
+    /// \brief Returns the column with the given ID.
+    ///
+    /// \pre The argument should be a valid column ID in the LP problem.
+    static Col colFromId(int id) { return Col(id); }
 
     ///Refer to a row of the LP.
@@ -174,59 +184,91 @@
     ///other rows.
     ///
-    ///\todo Document what can one do with a Row (INVALID, comparing,
-    ///it is similar to Node/Edge)
+    ///\note This class is similar to other Item types in LEMON, like
+    ///Node and Arc types in digraph.
     class Row {
+      friend class LpBase;
     protected:
-      int id;
-      friend class LpSolverBase;
-      explicit Row(int _id) : id(_id) {}
+      int _id;
+      explicit Row(int id) : _id(id) {}
     public:
       typedef Value ExprValue;
-      typedef True LpSolverRow;
+      typedef True LpRow;
+      /// Default constructor
+      
+      /// \warning The default constructor sets the Row to an
+      /// undefined value.
       Row() {}
-      Row(const Invalid&) : id(-1) {}
-
-      bool operator< (Row c) const  {return id< c.id;}
-      bool operator> (Row c) const  {return id> c.id;}
-      bool operator==(Row c) const  {return id==c.id;}
-      bool operator!=(Row c) const  {return id!=c.id;}
+      /// Invalid constructor \& conversion.
+      
+      /// This constructor initializes the Row to be invalid.
+      /// \sa Invalid for more details.      
+      Row(const Invalid&) : _id(-1) {}
+      /// Equality operator
+
+      /// Two \ref Row "Row"s are equal if and only if they point to
+      /// the same LP row or both are invalid.
+      bool operator==(Row r) const  {return _id == r._id;}
+      /// Inequality operator
+      
+      /// \sa operator==(Row r)
+      ///
+      bool operator!=(Row r) const  {return _id != r._id;}
+      /// Artificial ordering operator.
+
+      /// To allow the use of this object in std::map or similar
+      /// associative container we require this.
+      ///
+      /// \note This operator only have to define some strict ordering of
+      /// the items; this order has nothing to do with the iteration
+      /// ordering of the items.
+      bool operator<(Row r) const  {return _id < r._id;}
     };
 
+    ///Iterator for iterate over the rows of an LP problem
+
+    /// Its usage is quite simple, for example you can count the number
+    /// of rows in an LP \c lp:
+    ///\code
+    /// int count=0;
+    /// for (LpBase::RowIt c(lp); c!=INVALID; ++c) ++count;
+    ///\endcode
     class RowIt : public Row {
-      const LpSolverBase *_lp;
+      const LpBase *_solver;
     public:
+      /// Default constructor
+      
+      /// \warning The default constructor sets the iterator
+      /// to an undefined value.
       RowIt() {}
-      RowIt(const LpSolverBase &lp) : _lp(&lp)
+      /// Sets the iterator to the first Row
+      
+      /// Sets the iterator to the first Row.
+      ///
+      RowIt(const LpBase &solver) : _solver(&solver)
       {
-        _lp->rows.firstFix(id);
-      }
+        _solver->rows.firstItem(_id);
+      }
+      /// Invalid constructor \& conversion
+      
+      /// Initialize the iterator to be invalid.
+      /// \sa Invalid for more details.
       RowIt(const Invalid&) : Row(INVALID) {}
+      /// Next row
+      
+      /// Assign the iterator to the next row.
+      ///
       RowIt &operator++()
       {
-        _lp->rows.nextFix(id);
+        _solver->rows.nextItem(_id);
         return *this;
       }
     };
 
-    static int id(const Row& row) { return row.id; }
-
-  protected:
-
-    int _lpId(const Col& c) const {
-      return cols.floatingId(id(c));
-    }
-
-    int _lpId(const Row& r) const {
-      return rows.floatingId(id(r));
-    }
-
-    Col _item(int i, Col) const {
-      return Col(cols.fixId(i));
-    }
-
-    Row _item(int i, Row) const {
-      return Row(rows.fixId(i));
-    }
-
+    /// \brief Returns the ID of the row.
+    static int id(const Row& row) { return row._id; }
+    /// \brief Returns the row with the given ID.
+    ///
+    /// \pre The argument should be a valid row ID in the LP problem.
+    static Row rowFromId(int id) { return Row(id); }
 
   public:
@@ -239,8 +281,4 @@
     ///There are several ways to access and modify the contents of this
     ///container.
-    ///- Its it fully compatible with \c std::map<Col,double>, so for expamle
-    ///if \c e is an Expr and \c v and \c w are of type \ref Col, then you can
-    ///read and modify the coefficients like
-    ///these.
     ///\code
     ///e[v]=5;
@@ -251,8 +289,8 @@
     ///\code
     ///double s=0;
-    ///for(LpSolverBase::Expr::iterator i=e.begin();i!=e.end();++i)
-    ///  s+=i->second;
+    ///for(LpBase::Expr::ConstCoeffIt i(e);i!=INVALID;++i)
+    ///  s+=*i * primal(i);
     ///\endcode
-    ///(This code computes the sum of all coefficients).
+    ///(This code computes the primal value of the expression).
     ///- Numbers (<tt>double</tt>'s)
     ///and variables (\ref Col "Col"s) directly convert to an
@@ -263,5 +301,5 @@
     ///v*2.1+(3*v+(v*12+w+6)*3)/2
     ///\endcode
-    ///are valid \ref Expr "Expr"essions.
+    ///are valid expressions.
     ///The usual assignment operations are also defined.
     ///\code
@@ -271,102 +309,215 @@
     ///e/=5;
     ///\endcode
-    ///- The constant member can be set and read by \ref constComp()
+    ///- The constant member can be set and read by dereference
+    ///  operator (unary *)
+    ///
     ///\code
-    ///e.constComp()=12;
-    ///double c=e.constComp();
+    ///*e=12;
+    ///double c=*e;
     ///\endcode
     ///
-    ///\note \ref clear() not only sets all coefficients to 0 but also
-    ///clears the constant components.
-    ///
     ///\sa Constr
-    ///
-    class Expr : public std::map<Col,Value>
-    {
+    class Expr {
+      friend class LpBase;
     public:
-      typedef LpSolverBase::Col Key;
-      typedef LpSolverBase::Value Value;
+      /// The key type of the expression
+      typedef LpBase::Col Key;
+      /// The value type of the expression
+      typedef LpBase::Value Value;
 
     protected:
-      typedef std::map<Col,Value> Base;
-
       Value const_comp;
+      std::map<int, Value> comps;
+
     public:
-      typedef True IsLinExpression;
-      ///\e
-      Expr() : Base(), const_comp(0) { }
-      ///\e
-      Expr(const Key &v) : const_comp(0) {
-        Base::insert(std::make_pair(v, 1));
-      }
-      ///\e
+      typedef True SolverExpr;
+      /// Default constructor
+      
+      /// Construct an empty expression, the coefficients and
+      /// the constant component are initialized to zero.
+      Expr() : const_comp(0) {}
+      /// Construct an expression from a column
+
+      /// Construct an expression, which has a term with \c c variable
+      /// and 1.0 coefficient.
+      Expr(const Col &c) : const_comp(0) {
+        typedef std::map<int, Value>::value_type pair_type;
+        comps.insert(pair_type(id(c), 1));
+      }
+      /// Construct an expression from a constant
+
+      /// Construct an expression, which's constant component is \c v.
+      ///
       Expr(const Value &v) : const_comp(v) {}
-      ///\e
-      void set(const Key &v,const Value &c) {
-        Base::insert(std::make_pair(v, c));
-      }
-      ///\e
-      Value &constComp() { return const_comp; }
-      ///\e
-      const Value &constComp() const { return const_comp; }
-
-      ///Removes the components with zero coefficient.
-      void simplify() {
-        for (Base::iterator i=Base::begin(); i!=Base::end();) {
-          Base::iterator j=i;
-          ++j;
-          if ((*i).second==0) Base::erase(i);
-          i=j;
+      /// Returns the coefficient of the column
+      Value operator[](const Col& c) const {
+        std::map<int, Value>::const_iterator it=comps.find(id(c));
+        if (it != comps.end()) {
+          return it->second;
+        } else {
+          return 0;
         }
       }
-
-      void simplify() const {
-        const_cast<Expr*>(this)->simplify();
-      }
-
-      ///Removes the coefficients closer to zero than \c tolerance.
-      void simplify(double &tolerance) {
-        for (Base::iterator i=Base::begin(); i!=Base::end();) {
-          Base::iterator j=i;
-          ++j;
-          if (std::fabs((*i).second)<tolerance) Base::erase(i);
-          i=j;
+      /// Returns the coefficient of the column
+      Value& operator[](const Col& c) {
+        return comps[id(c)];
+      }
+      /// Sets the coefficient of the column
+      void set(const Col &c, const Value &v) {
+        if (v != 0.0) {
+          typedef std::map<int, Value>::value_type pair_type;
+          comps.insert(pair_type(id(c), v));
+        } else {
+          comps.erase(id(c));
         }
+      }
+      /// Returns the constant component of the expression
+      Value& operator*() { return const_comp; }
+      /// Returns the constant component of the expression
+      const Value& operator*() const { return const_comp; }
+      /// \brief Removes the coefficients which's absolute value does
+      /// not exceed \c epsilon. It also sets to zero the constant
+      /// component, if it does not exceed epsilon in absolute value.
+      void simplify(Value epsilon = 0.0) {
+        std::map<int, Value>::iterator it=comps.begin();
+        while (it != comps.end()) {
+          std::map<int, Value>::iterator jt=it;
+          ++jt;
+          if (std::fabs((*it).second) <= epsilon) comps.erase(it);
+          it=jt;
+        }
+        if (std::fabs(const_comp) <= epsilon) const_comp = 0;
+      }
+
+      void simplify(Value epsilon = 0.0) const {
+        const_cast<Expr*>(this)->simplify(epsilon);
       }
 
       ///Sets all coefficients and the constant component to 0.
       void clear() {
-        Base::clear();
+        comps.clear();
         const_comp=0;
       }
 
-      ///\e
+      ///Compound assignment
       Expr &operator+=(const Expr &e) {
-        for (Base::const_iterator j=e.begin(); j!=e.end(); ++j)
-          (*this)[j->first]+=j->second;
+        for (std::map<int, Value>::const_iterator it=e.comps.begin();
+             it!=e.comps.end(); ++it)
+          comps[it->first]+=it->second;
         const_comp+=e.const_comp;
         return *this;
       }
-      ///\e
+      ///Compound assignment
       Expr &operator-=(const Expr &e) {
-        for (Base::const_iterator j=e.begin(); j!=e.end(); ++j)
-          (*this)[j->first]-=j->second;
+        for (std::map<int, Value>::const_iterator it=e.comps.begin();
+             it!=e.comps.end(); ++it)
+          comps[it->first]-=it->second;
         const_comp-=e.const_comp;
         return *this;
       }
-      ///\e
-      Expr &operator*=(const Value &c) {
-        for (Base::iterator j=Base::begin(); j!=Base::end(); ++j)
-          j->second*=c;
-        const_comp*=c;
+      ///Multiply with a constant
+      Expr &operator*=(const Value &v) {
+        for (std::map<int, Value>::iterator it=comps.begin();
+             it!=comps.end(); ++it)
+          it->second*=v;
+        const_comp*=v;
         return *this;
       }
-      ///\e
+      ///Division with a constant
       Expr &operator/=(const Value &c) {
-        for (Base::iterator j=Base::begin(); j!=Base::end(); ++j)
-          j->second/=c;
+        for (std::map<int, Value>::iterator it=comps.begin();
+             it!=comps.end(); ++it)
+          it->second/=c;
         const_comp/=c;
         return *this;
       }
+
+      ///Iterator over the expression
+      
+      ///The iterator iterates over the terms of the expression. 
+      /// 
+      ///\code
+      ///double s=0;
+      ///for(LpBase::Expr::CoeffIt i(e);i!=INVALID;++i)
+      ///  s+= *i * primal(i);
+      ///\endcode
+      class CoeffIt {
+      private:
+
+        std::map<int, Value>::iterator _it, _end;
+
+      public:
+
+        /// Sets the iterator to the first term
+        
+        /// Sets the iterator to the first term of the expression.
+        ///
+        CoeffIt(Expr& e)
+          : _it(e.comps.begin()), _end(e.comps.end()){}
+
+        /// Convert the iterator to the column of the term
+        operator Col() const {
+          return colFromId(_it->first);
+        }
+
+        /// Returns the coefficient of the term
+        Value& operator*() { return _it->second; }
+
+        /// Returns the coefficient of the term
+        const Value& operator*() const { return _it->second; }
+        /// Next term
+        
+        /// Assign the iterator to the next term.
+        ///
+        CoeffIt& operator++() { ++_it; return *this; }
+
+        /// Equality operator
+        bool operator==(Invalid) const { return _it == _end; }
+        /// Inequality operator
+        bool operator!=(Invalid) const { return _it != _end; }
+      };
+
+      /// Const iterator over the expression
+      
+      ///The iterator iterates over the terms of the expression. 
+      /// 
+      ///\code
+      ///double s=0;
+      ///for(LpBase::Expr::ConstCoeffIt i(e);i!=INVALID;++i)
+      ///  s+=*i * primal(i);
+      ///\endcode
+      class ConstCoeffIt {
+      private:
+
+        std::map<int, Value>::const_iterator _it, _end;
+
+      public:
+
+        /// Sets the iterator to the first term
+        
+        /// Sets the iterator to the first term of the expression.
+        ///
+        ConstCoeffIt(const Expr& e)
+          : _it(e.comps.begin()), _end(e.comps.end()){}
+
+        /// Convert the iterator to the column of the term
+        operator Col() const {
+          return colFromId(_it->first);
+        }
+
+        /// Returns the coefficient of the term
+        const Value& operator*() const { return _it->second; }
+
+        /// Next term
+        
+        /// Assign the iterator to the next term.
+        ///
+        ConstCoeffIt& operator++() { ++_it; return *this; }
+
+        /// Equality operator
+        bool operator==(Invalid) const { return _it == _end; }
+        /// Inequality operator
+        bool operator!=(Invalid) const { return _it != _end; }
+      };
 
     };
@@ -395,11 +546,11 @@
     ///  e>=t
     ///\endcode
-    ///\warning The validity of a constraint is checked only at run time, so
-    ///e.g. \ref addRow(<tt>x[1]\<=x[2]<=5</tt>) will compile, but will throw 
-    ///an assertion.
+    ///\warning The validity of a constraint is checked only at run
+    ///time, so e.g. \ref addRow(<tt>x[1]\<=x[2]<=5</tt>) will
+    ///compile, but will fail an assertion.
     class Constr
     {
     public:
-      typedef LpSolverBase::Expr Expr;
+      typedef LpBase::Expr Expr;
       typedef Expr::Key Key;
       typedef Expr::Value Value;
@@ -412,13 +563,6 @@
       Constr() : _expr(), _lb(NaN), _ub(NaN) {}
       ///\e
-      Constr(Value lb,const Expr &e,Value ub) :
+      Constr(Value lb, const Expr &e, Value ub) :
         _expr(e), _lb(lb), _ub(ub) {}
-      ///\e
-      Constr(const Expr &e,Value ub) :
-        _expr(e), _lb(NaN), _ub(ub) {}
-      ///\e
-      Constr(Value lb,const Expr &e) :
-        _expr(e), _lb(lb), _ub(NaN) {}
-      ///\e
       Constr(const Expr &e) :
         _expr(e), _lb(NaN), _ub(NaN) {}
@@ -454,9 +598,9 @@
       ///Is the constraint lower bounded?
       bool lowerBounded() const {
-        return isFinite(_lb);
+        return _lb != -INF && !std::isnan(_lb);
       }
       ///Is the constraint upper bounded?
       bool upperBounded() const {
-        return isFinite(_ub);
+        return _ub != INF && !std::isnan(_ub);
       }
 
@@ -471,9 +615,4 @@
     ///There are several ways to access and modify the contents of this
     ///container.
-    ///- Its it fully compatible with \c std::map<Row,double>, so for expamle
-    ///if \c e is an DualExpr and \c v
-    ///and \c w are of type \ref Row, then you can
-    ///read and modify the coefficients like
-    ///these.
     ///\code
     ///e[v]=5;
@@ -484,6 +623,6 @@
     ///\code
     ///double s=0;
-    ///for(LpSolverBase::DualExpr::iterator i=e.begin();i!=e.end();++i)
-    ///  s+=i->second;
+    ///for(LpBase::DualExpr::ConstCoeffIt i(e);i!=INVALID;++i)
+    ///  s+=*i;
     ///\endcode
     ///(This code computes the sum of all coefficients).
@@ -496,5 +635,5 @@
     ///v*2.1+(3*v+(v*12+w)*3)/2
     ///\endcode
-    ///are valid \ref DualExpr "DualExpr"essions.
+    ///are valid \ref DualExpr dual expressions.
     ///The usual assignment operations are also defined.
     ///\code
@@ -506,90 +645,201 @@
     ///
     ///\sa Expr
-    ///
-    class DualExpr : public std::map<Row,Value>
-    {
+    class DualExpr {
+      friend class LpBase;
     public:
-      typedef LpSolverBase::Row Key;
-      typedef LpSolverBase::Value Value;
+      /// The key type of the expression
+      typedef LpBase::Row Key;
+      /// The value type of the expression
+      typedef LpBase::Value Value;
 
     protected:
-      typedef std::map<Row,Value> Base;
+      std::map<int, Value> comps;
 
     public:
-      typedef True IsLinExpression;
-      ///\e
-      DualExpr() : Base() { }
-      ///\e
-      DualExpr(const Key &v) {
-        Base::insert(std::make_pair(v, 1));
-      }
-      ///\e
-      void set(const Key &v,const Value &c) {
-        Base::insert(std::make_pair(v, c));
-      }
-
-      ///Removes the components with zero coefficient.
-      void simplify() {
-        for (Base::iterator i=Base::begin(); i!=Base::end();) {
-          Base::iterator j=i;
-          ++j;
-          if ((*i).second==0) Base::erase(i);
-          i=j;
+      typedef True SolverExpr;
+      /// Default constructor
+      
+      /// Construct an empty expression, the coefficients are
+      /// initialized to zero.
+      DualExpr() {}
+      /// Construct an expression from a row
+
+      /// Construct an expression, which has a term with \c r dual
+      /// variable and 1.0 coefficient.
+      DualExpr(const Row &r) {
+        typedef std::map<int, Value>::value_type pair_type;
+        comps.insert(pair_type(id(r), 1));
+      }
+      /// Returns the coefficient of the row
+      Value operator[](const Row& r) const {
+        std::map<int, Value>::const_iterator it = comps.find(id(r));
+        if (it != comps.end()) {
+          return it->second;
+        } else {
+          return 0;
         }
       }
-
-      void simplify() const {
-        const_cast<DualExpr*>(this)->simplify();
-      }
-
-      ///Removes the coefficients closer to zero than \c tolerance.
-      void simplify(double &tolerance) {
-        for (Base::iterator i=Base::begin(); i!=Base::end();) {
-          Base::iterator j=i;
-          ++j;
-          if (std::fabs((*i).second)<tolerance) Base::erase(i);
-          i=j;
+      /// Returns the coefficient of the row
+      Value& operator[](const Row& r) {
+        return comps[id(r)];
+      }
+      /// Sets the coefficient of the row
+      void set(const Row &r, const Value &v) {
+        if (v != 0.0) {
+          typedef std::map<int, Value>::value_type pair_type;
+          comps.insert(pair_type(id(r), v));
+        } else {
+          comps.erase(id(r));
         }
+      }
+      /// \brief Removes the coefficients which's absolute value does
+      /// not exceed \c epsilon. 
+      void simplify(Value epsilon = 0.0) {
+        std::map<int, Value>::iterator it=comps.begin();
+        while (it != comps.end()) {
+          std::map<int, Value>::iterator jt=it;
+          ++jt;
+          if (std::fabs((*it).second) <= epsilon) comps.erase(it);
+          it=jt;
+        }
+      }
+
+      void simplify(Value epsilon = 0.0) const {
+        const_cast<DualExpr*>(this)->simplify(epsilon);
       }
 
       ///Sets all coefficients to 0.
       void clear() {
-        Base::clear();
-      }
-
-      ///\e
+        comps.clear();
+      }
+      ///Compound assignment
       DualExpr &operator+=(const DualExpr &e) {
-        for (Base::const_iterator j=e.begin(); j!=e.end(); ++j)
-          (*this)[j->first]+=j->second;
+        for (std::map<int, Value>::const_iterator it=e.comps.begin();
+             it!=e.comps.end(); ++it)
+          comps[it->first]+=it->second;
         return *this;
       }
-      ///\e
+      ///Compound assignment
       DualExpr &operator-=(const DualExpr &e) {
-        for (Base::const_iterator j=e.begin(); j!=e.end(); ++j)
-          (*this)[j->first]-=j->second;
+        for (std::map<int, Value>::const_iterator it=e.comps.begin();
+             it!=e.comps.end(); ++it)
+          comps[it->first]-=it->second;
         return *this;
       }
-      ///\e
-      DualExpr &operator*=(const Value &c) {
-        for (Base::iterator j=Base::begin(); j!=Base::end(); ++j)
-          j->second*=c;
+      ///Multiply with a constant
+      DualExpr &operator*=(const Value &v) {
+        for (std::map<int, Value>::iterator it=comps.begin();
+             it!=comps.end(); ++it)
+          it->second*=v;
         return *this;
       }
-      ///\e
-      DualExpr &operator/=(const Value &c) {
-        for (Base::iterator j=Base::begin(); j!=Base::end(); ++j)
-          j->second/=c;
+      ///Division with a constant
+      DualExpr &operator/=(const Value &v) {
+        for (std::map<int, Value>::iterator it=comps.begin();
+             it!=comps.end(); ++it)
+          it->second/=v;
         return *this;
       }
+
+      ///Iterator over the expression
+      
+      ///The iterator iterates over the terms of the expression. 
+      /// 
+      ///\code
+      ///double s=0;
+      ///for(LpBase::DualExpr::CoeffIt i(e);i!=INVALID;++i)
+      ///  s+= *i * dual(i);
+      ///\endcode
+      class CoeffIt {
+      private:
+
+        std::map<int, Value>::iterator _it, _end;
+
+      public:
+
+        /// Sets the iterator to the first term
+        
+        /// Sets the iterator to the first term of the expression.
+        ///
+        CoeffIt(DualExpr& e)
+          : _it(e.comps.begin()), _end(e.comps.end()){}
+
+        /// Convert the iterator to the row of the term
+        operator Row() const {
+          return rowFromId(_it->first);
+        }
+
+        /// Returns the coefficient of the term
+        Value& operator*() { return _it->second; }
+
+        /// Returns the coefficient of the term
+        const Value& operator*() const { return _it->second; }
+
+        /// Next term
+        
+        /// Assign the iterator to the next term.
+        ///
+        CoeffIt& operator++() { ++_it; return *this; }
+
+        /// Equality operator
+        bool operator==(Invalid) const { return _it == _end; }
+        /// Inequality operator
+        bool operator!=(Invalid) const { return _it != _end; }
+      };
+
+      ///Iterator over the expression
+      
+      ///The iterator iterates over the terms of the expression. 
+      /// 
+      ///\code
+      ///double s=0;
+      ///for(LpBase::DualExpr::ConstCoeffIt i(e);i!=INVALID;++i)
+      ///  s+= *i * dual(i);
+      ///\endcode
+      class ConstCoeffIt {
+      private:
+
+        std::map<int, Value>::const_iterator _it, _end;
+
+      public:
+
+        /// Sets the iterator to the first term
+        
+        /// Sets the iterator to the first term of the expression.
+        ///
+        ConstCoeffIt(const DualExpr& e)
+          : _it(e.comps.begin()), _end(e.comps.end()){}
+
+        /// Convert the iterator to the row of the term
+        operator Row() const {
+          return rowFromId(_it->first);
+        }
+
+        /// Returns the coefficient of the term
+        const Value& operator*() const { return _it->second; }
+
+        /// Next term
+        
+        /// Assign the iterator to the next term.
+        ///
+        ConstCoeffIt& operator++() { ++_it; return *this; }
+
+        /// Equality operator
+        bool operator==(Invalid) const { return _it == _end; }
+        /// Inequality operator
+        bool operator!=(Invalid) const { return _it != _end; }
+      };
     };
 
 
-  private:
-
-    template <typename _Expr>
-    class MappedOutputIterator {
+  protected:
+
+    class InsertIterator {
+    private:
+
+      std::map<int, Value>& _host;
+      const _solver_bits::VarIndex& _index;
+
     public:
-
-      typedef std::insert_iterator<_Expr> Base;
 
       typedef std::output_iterator_tag iterator_category;
@@ -599,51 +849,31 @@
       typedef void pointer;
 
-      MappedOutputIterator(const Base& _base, const LpSolverBase& _lp)
-        : base(_base), lp(_lp) {}
-
-      MappedOutputIterator& operator*() {
+      InsertIterator(std::map<int, Value>& host,
+                   const _solver_bits::VarIndex& index)
+        : _host(host), _index(index) {}
+
+      InsertIterator& operator=(const std::pair<int, Value>& value) {
+        typedef std::map<int, Value>::value_type pair_type;
+        _host.insert(pair_type(_index[value.first], value.second));
         return *this;
       }
 
-      MappedOutputIterator& operator=(const std::pair<int, Value>& value) {
-        *base = std::make_pair(lp._item(value.first, typename _Expr::Key()),
-                               value.second);
-        return *this;
-      }
-
-      MappedOutputIterator& operator++() {
-        ++base;
-        return *this;
-      }
-
-      MappedOutputIterator operator++(int) {
-        MappedOutputIterator tmp(*this);
-        ++base;
-        return tmp;
-      }
-
-      bool operator==(const MappedOutputIterator& it) const {
-        return base == it.base;
-      }
-
-      bool operator!=(const MappedOutputIterator& it) const {
-        return base != it.base;
-      }
-
+      InsertIterator& operator*() { return *this; }
+      InsertIterator& operator++() { return *this; }
+      InsertIterator operator++(int) { return *this; }
+
+    };
+
+    class ExprIterator {
     private:
-      Base base;
-      const LpSolverBase& lp;
-    };
-
-    template <typename Expr>
-    class MappedInputIterator {
+      std::map<int, Value>::const_iterator _host_it;
+      const _solver_bits::VarIndex& _index;
     public:
 
-      typedef typename Expr::const_iterator Base;
-
-      typedef typename Base::iterator_category iterator_category;
-      typedef typename Base::difference_type difference_type;
+      typedef std::bidirectional_iterator_tag iterator_category;
+      typedef std::ptrdiff_t difference_type;
       typedef const std::pair<int, Value> value_type;
       typedef value_type reference;
+
       class pointer {
       public:
@@ -654,9 +884,10 @@
       };
 
-      MappedInputIterator(const Base& _base, const LpSolverBase& _lp)
-        : base(_base), lp(_lp) {}
+      ExprIterator(const std::map<int, Value>::const_iterator& host_it,
+                   const _solver_bits::VarIndex& index)
+        : _host_it(host_it), _index(index) {}
 
       reference operator*() {
-        return std::make_pair(lp._lpId(base->first), base->second);
+        return std::make_pair(_index(_host_it->first), _host_it->second);
       }
 
@@ -665,69 +896,35 @@
       }
 
-      MappedInputIterator& operator++() {
-        ++base;
-        return *this;
-      }
-
-      MappedInputIterator operator++(int) {
-        MappedInputIterator tmp(*this);
-        ++base;
-        return tmp;
-      }
-
-      bool operator==(const MappedInputIterator& it) const {
-        return base == it.base;
-      }
-
-      bool operator!=(const MappedInputIterator& it) const {
-        return base != it.base;
-      }
-
-    private:
-      Base base;
-      const LpSolverBase& lp;
+      ExprIterator& operator++() { ++_host_it; return *this; }
+      ExprIterator operator++(int) {
+        ExprIterator tmp(*this); ++_host_it; return tmp;
+      }
+
+      ExprIterator& operator--() { --_host_it; return *this; }
+      ExprIterator operator--(int) {
+        ExprIterator tmp(*this); --_host_it; return tmp;
+      }
+
+      bool operator==(const ExprIterator& it) const {
+        return _host_it == it._host_it;
+      }
+
+      bool operator!=(const ExprIterator& it) const {
+        return _host_it != it._host_it;
+      }
+
     };
 
   protected:
 
-    /// STL compatible iterator for lp col
-    typedef MappedInputIterator<Expr> ConstRowIterator;
-    /// STL compatible iterator for lp row
-    typedef MappedInputIterator<DualExpr> ConstColIterator;
-
-    /// STL compatible iterator for lp col
-    typedef MappedOutputIterator<Expr> RowIterator;
-    /// STL compatible iterator for lp row
-    typedef MappedOutputIterator<DualExpr> ColIterator;
-
     //Abstract virtual functions
-    virtual LpSolverBase* _newLp() = 0;
-    virtual LpSolverBase* _copyLp(){
-      LpSolverBase* newlp = _newLp();
-
-      std::map<Col, Col> ref;
-      for (LpSolverBase::ColIt it(*this); it != INVALID; ++it) {
-        Col ccol = newlp->addCol();
-        ref[it] = ccol;
-        newlp->colName(ccol, colName(it));
-        newlp->colLowerBound(ccol, colLowerBound(it));
-        newlp->colUpperBound(ccol, colUpperBound(it));
-      }
-
-      for (LpSolverBase::RowIt it(*this); it != INVALID; ++it) {
-        Expr e = row(it), ce;
-        for (Expr::iterator jt = e.begin(); jt != e.end(); ++jt) {
-          ce[ref[jt->first]] = jt->second;
-        }
-        ce += e.constComp();
-        Row r = newlp->addRow(ce);
-
-        double lower, upper;
-        getRowBounds(it, lower, upper);
-        newlp->rowBounds(r, lower, upper);
-      }
-
-      return newlp;
-    };
+    virtual LpBase* _newSolver() const = 0;
+    virtual LpBase* _cloneSolver() const = 0;
+
+    virtual int _addColId(int col) { return cols.addIndex(col); }
+    virtual int _addRowId(int row) { return rows.addIndex(row); }
+
+    virtual void _eraseColId(int col) { cols.eraseIndex(col); }
+    virtual void _eraseRowId(int row) { rows.eraseIndex(row); }
 
     virtual int _addCol() = 0;
@@ -737,41 +934,45 @@
     virtual void _eraseRow(int row) = 0;
 
-    virtual void _getColName(int col, std::string & name) const = 0;
-    virtual void _setColName(int col, const std::string & name) = 0;
+    virtual void _getColName(int col, std::string& name) const = 0;
+    virtual void _setColName(int col, const std::string& name) = 0;
     virtual int _colByName(const std::string& name) const = 0;
 
-    virtual void _setRowCoeffs(int i, ConstRowIterator b,
-                               ConstRowIterator e) = 0;
-    virtual void _getRowCoeffs(int i, RowIterator b) const = 0;
-    virtual void _setColCoeffs(int i, ConstColIterator b,
-                               ConstColIterator e) = 0;
-    virtual void _getColCoeffs(int i, ColIterator b) const = 0;
+    virtual void _getRowName(int row, std::string& name) const = 0;
+    virtual void _setRowName(int row, const std::string& name) = 0;
+    virtual int _rowByName(const std::string& name) const = 0;
+
+    virtual void _setRowCoeffs(int i, ExprIterator b, ExprIterator e) = 0;
+    virtual void _getRowCoeffs(int i, InsertIterator b) const = 0;
+
+    virtual void _setColCoeffs(int i, ExprIterator b, ExprIterator e) = 0;
+    virtual void _getColCoeffs(int i, InsertIterator b) const = 0;
+
     virtual void _setCoeff(int row, int col, Value value) = 0;
     virtual Value _getCoeff(int row, int col) const = 0;
+
     virtual void _setColLowerBound(int i, Value value) = 0;
     virtual Value _getColLowerBound(int i) const = 0;
+
     virtual void _setColUpperBound(int i, Value value) = 0;
     virtual Value _getColUpperBound(int i) const = 0;
-    virtual void _setRowBounds(int i, Value lower, Value upper) = 0;
-    virtual void _getRowBounds(int i, Value &lower, Value &upper) const = 0;
+
+    virtual void _setRowLowerBound(int i, Value value) = 0;
+    virtual Value _getRowLowerBound(int i) const = 0;
+
+    virtual void _setRowUpperBound(int i, Value value) = 0;
+    virtual Value _getRowUpperBound(int i) const = 0;
+
+    virtual void _setObjCoeffs(ExprIterator b, ExprIterator e) = 0;
+    virtual void _getObjCoeffs(InsertIterator b) const = 0;
 
     virtual void _setObjCoeff(int i, Value obj_coef) = 0;
     virtual Value _getObjCoeff(int i) const = 0;
-    virtual void _clearObj()=0;
-
-    virtual SolveExitStatus _solve() = 0;
-    virtual Value _getPrimal(int i) const = 0;
-    virtual Value _getDual(int i) const = 0;
-    virtual Value _getPrimalValue() const = 0;
-    virtual bool _isBasicCol(int i) const = 0;
-    virtual SolutionStatus _getPrimalStatus() const = 0;
-    virtual SolutionStatus _getDualStatus() const = 0;
-    virtual ProblemTypes _getProblemType() const = 0;
-
-    virtual void _setMax() = 0;
-    virtual void _setMin() = 0;
-
-
-    virtual bool _isMax() const = 0;
+
+    virtual void _setSense(Sense) = 0;
+    virtual Sense _getSense() const = 0;
+
+    virtual void _clear() = 0;
+
+    virtual const char* _solverName() const = 0;
 
     //Own protected stuff
@@ -780,16 +981,18 @@
     Value obj_const_comp;
 
+    LpBase() : rows(), cols(), obj_const_comp(0) {}
+
   public:
 
-    ///\e
-    LpSolverBase() : obj_const_comp(0) {}
-
-    ///\e
-    virtual ~LpSolverBase() {}
+    /// Virtual destructor
+    virtual ~LpBase() {}
 
     ///Creates a new LP problem
-    LpSolverBase* newLp() {return _newLp();}
+    LpBase* newSolver() {return _newSolver();}
     ///Makes a copy of the LP problem
-    LpSolverBase* copyLp() {return _copyLp();}
+    LpBase* cloneSolver() {return _cloneSolver();}
+
+    ///Gives back the name of the solver.
+    const char* solverName() const {return _solverName();}
 
     ///\name Build up and modify the LP
@@ -798,30 +1001,26 @@
 
     ///Add a new empty column (i.e a new variable) to the LP
-    Col addCol() { Col c; _addCol(); c.id = cols.addId(); return c;}
-
-    ///\brief Adds several new columns
-    ///(i.e a variables) at once
-    ///
-    ///This magic function takes a container as its argument
-    ///and fills its elements
-    ///with new columns (i.e. variables)
+    Col addCol() { Col c; c._id = _addColId(_addCol()); return c;}
+
+    ///\brief Adds several new columns (i.e variables) at once
+    ///
+    ///This magic function takes a container as its argument and fills
+    ///its elements with new columns (i.e. variables)
     ///\param t can be
     ///- a standard STL compatible iterable container with
-    ///\ref Col as its \c values_type
-    ///like
+    ///\ref Col as its \c values_type like
     ///\code
-    ///std::vector<LpSolverBase::Col>
-    ///std::list<LpSolverBase::Col>
+    ///std::vector<LpBase::Col>
+    ///std::list<LpBase::Col>
     ///\endcode
     ///- a standard STL compatible iterable container with
-    ///\ref Col as its \c mapped_type
-    ///like
+    ///\ref Col as its \c mapped_type like
     ///\code
-    ///std::map<AnyType,LpSolverBase::Col>
+    ///std::map<AnyType,LpBase::Col>
     ///\endcode
     ///- an iterable lemon \ref concepts::WriteMap "write map" like
     ///\code
-    ///ListGraph::NodeMap<LpSolverBase::Col>
-    ///ListGraph::EdgeMap<LpSolverBase::Col>
+    ///ListGraph::NodeMap<LpBase::Col>
+    ///ListGraph::ArcMap<LpBase::Col>
     ///\endcode
     ///\return The number of the created column.
@@ -831,5 +1030,5 @@
 #else
     template<class T>
-    typename enable_if<typename T::value_type::LpSolverCol,int>::type
+    typename enable_if<typename T::value_type::LpCol,int>::type
     addColSet(T &t,dummy<0> = 0) {
       int s=0;
@@ -838,5 +1037,5 @@
     }
     template<class T>
-    typename enable_if<typename T::value_type::second_type::LpSolverCol,
+    typename enable_if<typename T::value_type::second_type::LpCol,
                        int>::type
     addColSet(T &t,dummy<1> = 1) {
@@ -849,5 +1048,5 @@
     }
     template<class T>
-    typename enable_if<typename T::MapIt::Value::LpSolverCol,
+    typename enable_if<typename T::MapIt::Value::LpCol,
                        int>::type
     addColSet(T &t,dummy<2> = 2) {
@@ -867,17 +1066,17 @@
     ///\param e is a dual linear expression (see \ref DualExpr)
     ///a better one.
-    void col(Col c,const DualExpr &e) {
+    void col(Col c, const DualExpr &e) {
       e.simplify();
-      _setColCoeffs(_lpId(c), ConstColIterator(e.begin(), *this),
-                    ConstColIterator(e.end(), *this));
+      _setColCoeffs(cols(id(c)), ExprIterator(e.comps.begin(), cols),
+                    ExprIterator(e.comps.end(), cols));
     }
 
     ///Get a column (i.e a dual constraint) of the LP
 
-    ///\param r is the column to get
+    ///\param c is the column to get
     ///\return the dual expression associated to the column
     DualExpr col(Col c) const {
       DualExpr e;
-      _getColCoeffs(_lpId(c), ColIterator(std::inserter(e, e.end()), *this));
+      _getColCoeffs(cols(id(c)), InsertIterator(e.comps, rows));
       return e;
     }
@@ -886,5 +1085,5 @@
 
     ///\param e is a dual linear expression (see \ref DualExpr)
-    ///\param obj is the corresponding component of the objective
+    ///\param o is the corresponding component of the objective
     ///function. It is 0 by default.
     ///\return The created column.
@@ -900,30 +1099,26 @@
     ///This function adds a new empty row (i.e a new constraint) to the LP.
     ///\return The created row
-    Row addRow() { Row r; _addRow(); r.id = rows.addId(); return r;}
-
-    ///\brief Add several new rows
-    ///(i.e a constraints) at once
-    ///
-    ///This magic function takes a container as its argument
-    ///and fills its elements
-    ///with new row (i.e. variables)
+    Row addRow() { Row r; r._id = _addRowId(_addRow()); return r;}
+
+    ///\brief Add several new rows (i.e constraints) at once
+    ///
+    ///This magic function takes a container as its argument and fills
+    ///its elements with new row (i.e. variables)
     ///\param t can be
     ///- a standard STL compatible iterable container with
-    ///\ref Row as its \c values_type
-    ///like
+    ///\ref Row as its \c values_type like
     ///\code
-    ///std::vector<LpSolverBase::Row>
-    ///std::list<LpSolverBase::Row>
+    ///std::vector<LpBase::Row>
+    ///std::list<LpBase::Row>
     ///\endcode
     ///- a standard STL compatible iterable container with
-    ///\ref Row as its \c mapped_type
-    ///like
+    ///\ref Row as its \c mapped_type like
     ///\code
-    ///std::map<AnyType,LpSolverBase::Row>
+    ///std::map<AnyType,LpBase::Row>
     ///\endcode
     ///- an iterable lemon \ref concepts::WriteMap "write map" like
     ///\code
-    ///ListGraph::NodeMap<LpSolverBase::Row>
-    ///ListGraph::EdgeMap<LpSolverBase::Row>
+    ///ListGraph::NodeMap<LpBase::Row>
+    ///ListGraph::ArcMap<LpBase::Row>
     ///\endcode
     ///\return The number of rows created.
@@ -933,6 +1128,6 @@
 #else
     template<class T>
-    typename enable_if<typename T::value_type::LpSolverRow,int>::type
-    addRowSet(T &t,dummy<0> = 0) {
+    typename enable_if<typename T::value_type::LpRow,int>::type
+    addRowSet(T &t, dummy<0> = 0) {
       int s=0;
       for(typename T::iterator i=t.begin();i!=t.end();++i) {*i=addRow();s++;}
@@ -940,7 +1135,6 @@
     }
     template<class T>
-    typename enable_if<typename T::value_type::second_type::LpSolverRow,
-                       int>::type
-    addRowSet(T &t,dummy<1> = 1) {
+    typename enable_if<typename T::value_type::second_type::LpRow, int>::type
+    addRowSet(T &t, dummy<1> = 1) {
       int s=0;
       for(typename T::iterator i=t.begin();i!=t.end();++i) {
@@ -951,7 +1145,6 @@
     }
     template<class T>
-    typename enable_if<typename T::MapIt::Value::LpSolverRow,
-                       int>::type
-    addRowSet(T &t,dummy<2> = 2) {
+    typename enable_if<typename T::MapIt::Value::LpRow, int>::type
+    addRowSet(T &t, dummy<2> = 2) {
       int s=0;
       for(typename T::MapIt i(t); i!=INVALID; ++i)
@@ -970,13 +1163,10 @@
     ///\param e is a linear expression (see \ref Expr)
     ///\param u is the upper bound (\ref INF means no bound)
-    ///\bug This is a temporary function. The interface will change to
-    ///a better one.
-    ///\todo Option to control whether a constraint with a single variable is
-    ///added or not.
     void row(Row r, Value l, const Expr &e, Value u) {
       e.simplify();
-      _setRowCoeffs(_lpId(r), ConstRowIterator(e.begin(), *this),
-                    ConstRowIterator(e.end(), *this));
-      _setRowBounds(_lpId(r),l-e.constComp(),u-e.constComp());
+      _setRowCoeffs(rows(id(r)), ExprIterator(e.comps.begin(), cols),
+                    ExprIterator(e.comps.end(), cols));
+      _setRowLowerBound(rows(id(r)),l - *e);
+      _setRowUpperBound(rows(id(r)),u - *e);
     }
 
@@ -997,5 +1187,5 @@
     Expr row(Row r) const {
       Expr e;
-      _getRowCoeffs(_lpId(r), RowIterator(std::inserter(e, e.end()), *this));
+      _getRowCoeffs(rows(id(r)), InsertIterator(e.comps, cols));
       return e;
     }
@@ -1007,6 +1197,4 @@
     ///\param u is the upper bound (\ref INF means no bound)
     ///\return The created row.
-    ///\bug This is a temporary function. The interface will change to
-    ///a better one.
     Row addRow(Value l,const Expr &e, Value u) {
       Row r=addRow();
@@ -1024,28 +1212,26 @@
       return r;
     }
-    ///Erase a coloumn (i.e a variable) from the LP
-
-    ///\param c is the coloumn to be deleted
-    ///\todo Please check this
-    void eraseCol(Col c) {
-      _eraseCol(_lpId(c));
-      cols.eraseId(c.id);
-    }
-    ///Erase a  row (i.e a constraint) from the LP
+    ///Erase a column (i.e a variable) from the LP
+
+    ///\param c is the column to be deleted
+    void erase(Col c) {
+      _eraseCol(cols(id(c)));
+      _eraseColId(cols(id(c)));
+    }
+    ///Erase a row (i.e a constraint) from the LP
 
     ///\param r is the row to be deleted
-    ///\todo Please check this
-    void eraseRow(Row r) {
-      _eraseRow(_lpId(r));
-      rows.eraseId(r.id);
+    void erase(Row r) {
+      _eraseRow(rows(id(r)));
+      _eraseRowId(rows(id(r)));
     }
 
     /// Get the name of a column
 
-    ///\param c is the coresponding coloumn
+    ///\param c is the coresponding column
     ///\return The name of the colunm
     std::string colName(Col c) const {
       std::string name;
-      _getColName(_lpId(c), name);
+      _getColName(cols(id(c)), name);
       return name;
     }
@@ -1053,8 +1239,8 @@
     /// Set the name of a column
 
-    ///\param c is the coresponding coloumn
+    ///\param c is the coresponding column
     ///\param name The name to be given
     void colName(Col c, const std::string& name) {
-      _setColName(_lpId(c), name);
+      _setColName(cols(id(c)), name);
     }
 
@@ -1065,5 +1251,32 @@
     Col colByName(const std::string& name) const {
       int k = _colByName(name);
-      return k != -1 ? Col(cols.fixId(k)) : Col(INVALID);
+      return k != -1 ? Col(cols[k]) : Col(INVALID);
+    }
+
+    /// Get the name of a row
+
+    ///\param r is the coresponding row
+    ///\return The name of the row
+    std::string rowName(Row r) const {
+      std::string name;
+      _getRowName(rows(id(r)), name);
+      return name;
+    }
+
+    /// Set the name of a row
+
+    ///\param r is the coresponding row
+    ///\param name The name to be given
+    void rowName(Row r, const std::string& name) {
+      _setRowName(rows(id(r)), name);
+    }
+
+    /// Get the row by its name
+
+    ///\param name The name of the row
+    ///\return the proper row or \c INVALID
+    Row rowByName(const std::string& name) const {
+      int k = _rowByName(name);
+      return k != -1 ? Row(rows[k]) : Row(INVALID);
     }
 
@@ -1071,19 +1284,17 @@
 
     ///\param r is the row of the element to be modified
-    ///\param c is the coloumn of the element to be modified
+    ///\param c is the column of the element to be modified
     ///\param val is the new value of the coefficient
-
     void coeff(Row r, Col c, Value val) {
-      _setCoeff(_lpId(r),_lpId(c), val);
+      _setCoeff(rows(id(r)),cols(id(c)), val);
     }
 
     /// Get an element of the coefficient matrix of the LP
 
-    ///\param r is the row of the element in question
-    ///\param c is the coloumn of the element in question
+    ///\param r is the row of the element
+    ///\param c is the column of the element
     ///\return the corresponding coefficient
-
     Value coeff(Row r, Col c) const {
-      return _getCoeff(_lpId(r),_lpId(c));
+      return _getCoeff(rows(id(r)),cols(id(c)));
     }
 
@@ -1094,24 +1305,24 @@
     /// Value or -\ref INF.
     void colLowerBound(Col c, Value value) {
-      _setColLowerBound(_lpId(c),value);
+      _setColLowerBound(cols(id(c)),value);
     }
 
     /// Get the lower bound of a column (i.e a variable)
 
-    /// This function returns the lower bound for column (variable) \t c
+    /// This function returns the lower bound for column (variable) \c c
     /// (this might be -\ref INF as well).
-    ///\return The lower bound for coloumn \t c
+    ///\return The lower bound for column \c c
     Value colLowerBound(Col c) const {
-      return _getColLowerBound(_lpId(c));
+      return _getColLowerBound(cols(id(c)));
     }
 
     ///\brief Set the lower bound of  several columns
-    ///(i.e a variables) at once
+    ///(i.e variables) at once
     ///
     ///This magic function takes a container as its argument
     ///and applies the function on all of its elements.
-    /// The lower bound of a variable (column) has to be given by an
-    /// extended number of type Value, i.e. a finite number of type
-    /// Value or -\ref INF.
+    ///The lower bound of a variable (column) has to be given by an
+    ///extended number of type Value, i.e. a finite number of type
+    ///Value or -\ref INF.
 #ifdef DOXYGEN
     template<class T>
@@ -1119,5 +1330,5 @@
 #else
     template<class T>
-    typename enable_if<typename T::value_type::LpSolverCol,void>::type
+    typename enable_if<typename T::value_type::LpCol,void>::type
     colLowerBound(T &t, Value value,dummy<0> = 0) {
       for(typename T::iterator i=t.begin();i!=t.end();++i) {
@@ -1126,5 +1337,5 @@
     }
     template<class T>
-    typename enable_if<typename T::value_type::second_type::LpSolverCol,
+    typename enable_if<typename T::value_type::second_type::LpCol,
                        void>::type
     colLowerBound(T &t, Value value,dummy<1> = 1) {
@@ -1134,5 +1345,5 @@
     }
     template<class T>
-    typename enable_if<typename T::MapIt::Value::LpSolverCol,
+    typename enable_if<typename T::MapIt::Value::LpCol,
                        void>::type
     colLowerBound(T &t, Value value,dummy<2> = 2) {
@@ -1149,24 +1360,24 @@
     /// Value or \ref INF.
     void colUpperBound(Col c, Value value) {
-      _setColUpperBound(_lpId(c),value);
+      _setColUpperBound(cols(id(c)),value);
     };
 
     /// Get the upper bound of a column (i.e a variable)
 
-    /// This function returns the upper bound for column (variable) \t c
+    /// This function returns the upper bound for column (variable) \c c
     /// (this might be \ref INF as well).
-    ///\return The upper bound for coloumn \t c
+    /// \return The upper bound for column \c c
     Value colUpperBound(Col c) const {
-      return _getColUpperBound(_lpId(c));
+      return _getColUpperBound(cols(id(c)));
     }
 
     ///\brief Set the upper bound of  several columns
-    ///(i.e a variables) at once
+    ///(i.e variables) at once
     ///
     ///This magic function takes a container as its argument
     ///and applies the function on all of its elements.
-    /// The upper bound of a variable (column) has to be given by an
-    /// extended number of type Value, i.e. a finite number of type
-    /// Value or \ref INF.
+    ///The upper bound of a variable (column) has to be given by an
+    ///extended number of type Value, i.e. a finite number of type
+    ///Value or \ref INF.
 #ifdef DOXYGEN
     template<class T>
@@ -1174,5 +1385,5 @@
 #else
     template<class T>
-    typename enable_if<typename T::value_type::LpSolverCol,void>::type
+    typename enable_if<typename T::value_type::LpCol,void>::type
     colUpperBound(T &t, Value value,dummy<0> = 0) {
       for(typename T::iterator i=t.begin();i!=t.end();++i) {
@@ -1181,5 +1392,5 @@
     }
     template<class T>
-    typename enable_if<typename T::value_type::second_type::LpSolverCol,
+    typename enable_if<typename T::value_type::second_type::LpCol,
                        void>::type
     colUpperBound(T &t, Value value,dummy<1> = 1) {
@@ -1189,5 +1400,5 @@
     }
     template<class T>
-    typename enable_if<typename T::MapIt::Value::LpSolverCol,
+    typename enable_if<typename T::MapIt::Value::LpCol,
                        void>::type
     colUpperBound(T &t, Value value,dummy<2> = 2) {
@@ -1205,10 +1416,10 @@
     /// Value, -\ref INF or \ref INF.
     void colBounds(Col c, Value lower, Value upper) {
-      _setColLowerBound(_lpId(c),lower);
-      _setColUpperBound(_lpId(c),upper);
+      _setColLowerBound(cols(id(c)),lower);
+      _setColUpperBound(cols(id(c)),upper);
     }
 
     ///\brief Set the lower and the upper bound of several columns
-    ///(i.e a variables) at once
+    ///(i.e variables) at once
     ///
     ///This magic function takes a container as its argument
@@ -1223,5 +1434,5 @@
 #else
     template<class T>
-    typename enable_if<typename T::value_type::LpSolverCol,void>::type
+    typename enable_if<typename T::value_type::LpCol,void>::type
     colBounds(T &t, Value lower, Value upper,dummy<0> = 0) {
       for(typename T::iterator i=t.begin();i!=t.end();++i) {
@@ -1230,6 +1441,5 @@
     }
     template<class T>
-    typename enable_if<typename T::value_type::second_type::LpSolverCol,
-                       void>::type
+    typename enable_if<typename T::value_type::second_type::LpCol, void>::type
     colBounds(T &t, Value lower, Value upper,dummy<1> = 1) {
       for(typename T::iterator i=t.begin();i!=t.end();++i) {
@@ -1238,6 +1448,5 @@
     }
     template<class T>
-    typename enable_if<typename T::MapIt::Value::LpSolverCol,
-                       void>::type
+    typename enable_if<typename T::MapIt::Value::LpCol, void>::type
     colBounds(T &t, Value lower, Value upper,dummy<2> = 2) {
       for(typename T::MapIt i(t); i!=INVALID; ++i){
@@ -1247,74 +1456,369 @@
 #endif
 
-
-    /// Set the lower and the upper bounds of a row (i.e a constraint)
-
-    /// The lower and the upper bound of a constraint (row) have to be
-    /// given by an extended number of type Value, i.e. a finite
-    /// number of type Value, -\ref INF or \ref INF. There is no
-    /// separate function for the lower and the upper bound because
-    /// that would have been hard to implement for CPLEX.
-    void rowBounds(Row c, Value lower, Value upper) {
-      _setRowBounds(_lpId(c),lower, upper);
-    }
-
-    /// Get the lower and the upper bounds of a row (i.e a constraint)
-
-    /// The lower and the upper bound of
-    /// a constraint (row) are
-    /// extended numbers of type Value, i.e.  finite numbers of type
-    /// Value, -\ref INF or \ref INF.
-    /// \todo There is no separate function for the
-    /// lower and the upper bound because we had problems with the
-    /// implementation of the setting functions for CPLEX:
-    /// check out whether this can be done for these functions.
-    void getRowBounds(Row c, Value &lower, Value &upper) const {
-      _getRowBounds(_lpId(c),lower, upper);
+    /// Set the lower bound of a row (i.e a constraint)
+
+    /// The lower bound of a constraint (row) has to be given by an
+    /// extended number of type Value, i.e. a finite number of type
+    /// Value or -\ref INF.
+    void rowLowerBound(Row r, Value value) {
+      _setRowLowerBound(rows(id(r)),value);
+    }
+
+    /// Get the lower bound of a row (i.e a constraint)
+
+    /// This function returns the lower bound for row (constraint) \c c
+    /// (this might be -\ref INF as well).
+    ///\return The lower bound for row \c r
+    Value rowLowerBound(Row r) const {
+      return _getRowLowerBound(rows(id(r)));
+    }
+
+    /// Set the upper bound of a row (i.e a constraint)
+
+    /// The upper bound of a constraint (row) has to be given by an
+    /// extended number of type Value, i.e. a finite number of type
+    /// Value or -\ref INF.
+    void rowUpperBound(Row r, Value value) {
+      _setRowUpperBound(rows(id(r)),value);
+    }
+
+    /// Get the upper bound of a row (i.e a constraint)
+
+    /// This function returns the upper bound for row (constraint) \c c
+    /// (this might be -\ref INF as well).
+    ///\return The upper bound for row \c r
+    Value rowUpperBound(Row r) const {
+      return _getRowUpperBound(rows(id(r)));
     }
 
     ///Set an element of the objective function
-    void objCoeff(Col c, Value v) {_setObjCoeff(_lpId(c),v); };
+    void objCoeff(Col c, Value v) {_setObjCoeff(cols(id(c)),v); };
 
     ///Get an element of the objective function
-    Value objCoeff(Col c) const { return _getObjCoeff(_lpId(c)); };
+    Value objCoeff(Col c) const { return _getObjCoeff(cols(id(c))); };
 
     ///Set the objective function
 
     ///\param e is a linear expression of type \ref Expr.
-    void obj(Expr e) {
-      _clearObj();
-      for (Expr::iterator i=e.begin(); i!=e.end(); ++i)
-        objCoeff((*i).first,(*i).second);
-      obj_const_comp=e.constComp();
+    ///
+    void obj(const Expr& e) {
+      _setObjCoeffs(ExprIterator(e.comps.begin(), cols),
+                    ExprIterator(e.comps.end(), cols));
+      obj_const_comp = *e;
     }
 
     ///Get the objective function
 
-    ///\return the objective function as a linear expression of type \ref Expr.
+    ///\return the objective function as a linear expression of type
+    ///Expr.
     Expr obj() const {
       Expr e;
-      for (ColIt it(*this); it != INVALID; ++it) {
-        double c = objCoeff(it);
-        if (c != 0.0) {
-          e.insert(std::make_pair(it, c));
-        }
-      }
+      _getObjCoeffs(InsertIterator(e.comps, cols));
+      *e = obj_const_comp;
       return e;
     }
 
 
-    ///Maximize
-    void max() { _setMax(); }
-    ///Minimize
-    void min() { _setMin(); }
-
-    ///Query function: is this a maximization problem?
-    bool isMax() const {return _isMax(); }
-
-    ///Query function: is this a minimization problem?
-    bool isMin() const {return !isMax(); }
+    ///Set the direction of optimization
+    void sense(Sense sense) { _setSense(sense); }
+
+    ///Query the direction of the optimization
+    Sense sense() const {return _getSense(); }
+
+    ///Set the sense to maximization
+    void max() { _setSense(MAX); }
+
+    ///Set the sense to maximization
+    void min() { _setSense(MIN); }
+
+    ///Clears the problem
+    void clear() { _clear(); }
 
     ///@}
 
+  };
+
+  /// Addition
+
+  ///\relates LpBase::Expr
+  ///
+  inline LpBase::Expr operator+(const LpBase::Expr &a, const LpBase::Expr &b) {
+    LpBase::Expr tmp(a);
+    tmp+=b;
+    return tmp;
+  }
+  ///Substraction
+
+  ///\relates LpBase::Expr
+  ///
+  inline LpBase::Expr operator-(const LpBase::Expr &a, const LpBase::Expr &b) {
+    LpBase::Expr tmp(a);
+    tmp-=b;
+    return tmp;
+  }
+  ///Multiply with constant
+
+  ///\relates LpBase::Expr
+  ///
+  inline LpBase::Expr operator*(const LpBase::Expr &a, const LpBase::Value &b) {
+    LpBase::Expr tmp(a);
+    tmp*=b;
+    return tmp;
+  }
+
+  ///Multiply with constant
+
+  ///\relates LpBase::Expr
+  ///
+  inline LpBase::Expr operator*(const LpBase::Value &a, const LpBase::Expr &b) {
+    LpBase::Expr tmp(b);
+    tmp*=a;
+    return tmp;
+  }
+  ///Divide with constant
+
+  ///\relates LpBase::Expr
+  ///
+  inline LpBase::Expr operator/(const LpBase::Expr &a, const LpBase::Value &b) {
+    LpBase::Expr tmp(a);
+    tmp/=b;
+    return tmp;
+  }
+
+  ///Create constraint
+
+  ///\relates LpBase::Constr
+  ///
+  inline LpBase::Constr operator<=(const LpBase::Expr &e,
+                                   const LpBase::Expr &f) {
+    return LpBase::Constr(0, f - e, LpBase::INF);
+  }
+
+  ///Create constraint
+
+  ///\relates LpBase::Constr
+  ///
+  inline LpBase::Constr operator<=(const LpBase::Value &e,
+                                   const LpBase::Expr &f) {
+    return LpBase::Constr(e, f, LpBase::NaN);
+  }
+
+  ///Create constraint
+
+  ///\relates LpBase::Constr
+  ///
+  inline LpBase::Constr operator<=(const LpBase::Expr &e,
+                                   const LpBase::Value &f) {
+    return LpBase::Constr(- LpBase::INF, e, f);
+  }
+
+  ///Create constraint
+
+  ///\relates LpBase::Constr
+  ///
+  inline LpBase::Constr operator>=(const LpBase::Expr &e,
+                                   const LpBase::Expr &f) {
+    return LpBase::Constr(0, e - f, LpBase::INF);
+  }
+
+
+  ///Create constraint
+
+  ///\relates LpBase::Constr
+  ///
+  inline LpBase::Constr operator>=(const LpBase::Value &e,
+                                   const LpBase::Expr &f) {
+    return LpBase::Constr(LpBase::NaN, f, e);
+  }
+
+
+  ///Create constraint
+
+  ///\relates LpBase::Constr
+  ///
+  inline LpBase::Constr operator>=(const LpBase::Expr &e,
+                                   const LpBase::Value &f) {
+    return LpBase::Constr(f, e, LpBase::INF);
+  }
+
+  ///Create constraint
+
+  ///\relates LpBase::Constr
+  ///
+  inline LpBase::Constr operator==(const LpBase::Expr &e,
+                                   const LpBase::Value &f) {
+    return LpBase::Constr(f, e, f);
+  }
+
+  ///Create constraint
+
+  ///\relates LpBase::Constr
+  ///
+  inline LpBase::Constr operator==(const LpBase::Expr &e,
+                                   const LpBase::Expr &f) {
+    return LpBase::Constr(0, f - e, 0);
+  }
+
+  ///Create constraint
+
+  ///\relates LpBase::Constr
+  ///
+  inline LpBase::Constr operator<=(const LpBase::Value &n,
+                                   const LpBase::Constr &c) {
+    LpBase::Constr tmp(c);
+    LEMON_ASSERT(std::isnan(tmp.lowerBound()), "Wrong LP constraint");
+    tmp.lowerBound()=n;
+    return tmp;
+  }
+  ///Create constraint
+
+  ///\relates LpBase::Constr
+  ///
+  inline LpBase::Constr operator<=(const LpBase::Constr &c,
+                                   const LpBase::Value &n)
+  {
+    LpBase::Constr tmp(c);
+    LEMON_ASSERT(std::isnan(tmp.upperBound()), "Wrong LP constraint");
+    tmp.upperBound()=n;
+    return tmp;
+  }
+
+  ///Create constraint
+
+  ///\relates LpBase::Constr
+  ///
+  inline LpBase::Constr operator>=(const LpBase::Value &n,
+                                   const LpBase::Constr &c) {
+    LpBase::Constr tmp(c);
+    LEMON_ASSERT(std::isnan(tmp.upperBound()), "Wrong LP constraint");
+    tmp.upperBound()=n;
+    return tmp;
+  }
+  ///Create constraint
+
+  ///\relates LpBase::Constr
+  ///
+  inline LpBase::Constr operator>=(const LpBase::Constr &c,
+                                   const LpBase::Value &n)
+  {
+    LpBase::Constr tmp(c);
+    LEMON_ASSERT(std::isnan(tmp.lowerBound()), "Wrong LP constraint");
+    tmp.lowerBound()=n;
+    return tmp;
+  }
+
+  ///Addition
+
+  ///\relates LpBase::DualExpr
+  ///
+  inline LpBase::DualExpr operator+(const LpBase::DualExpr &a,
+                                    const LpBase::DualExpr &b) {
+    LpBase::DualExpr tmp(a);
+    tmp+=b;
+    return tmp;
+  }
+  ///Substraction
+
+  ///\relates LpBase::DualExpr
+  ///
+  inline LpBase::DualExpr operator-(const LpBase::DualExpr &a,
+                                    const LpBase::DualExpr &b) {
+    LpBase::DualExpr tmp(a);
+    tmp-=b;
+    return tmp;
+  }
+  ///Multiply with constant
+
+  ///\relates LpBase::DualExpr
+  ///
+  inline LpBase::DualExpr operator*(const LpBase::DualExpr &a,
+                                    const LpBase::Value &b) {
+    LpBase::DualExpr tmp(a);
+    tmp*=b;
+    return tmp;
+  }
+
+  ///Multiply with constant
+
+  ///\relates LpBase::DualExpr
+  ///
+  inline LpBase::DualExpr operator*(const LpBase::Value &a,
+                                    const LpBase::DualExpr &b) {
+    LpBase::DualExpr tmp(b);
+    tmp*=a;
+    return tmp;
+  }
+  ///Divide with constant
+
+  ///\relates LpBase::DualExpr
+  ///
+  inline LpBase::DualExpr operator/(const LpBase::DualExpr &a,
+                                    const LpBase::Value &b) {
+    LpBase::DualExpr tmp(a);
+    tmp/=b;
+    return tmp;
+  }
+
+  /// \ingroup lp_group
+  ///
+  /// \brief Common base class for LP solvers
+  ///
+  /// This class is an abstract base class for LP solvers. This class
+  /// provides a full interface for set and modify an LP problem,
+  /// solve it and retrieve the solution. You can use one of the
+  /// descendants as a concrete implementation, or the \c Lp
+  /// default LP solver. However, if you would like to handle LP
+  /// solvers as reference or pointer in a generic way, you can use
+  /// this class directly.
+  class LpSolver : virtual public LpBase {
+  public:
+
+    /// The problem types for primal and dual problems
+    enum ProblemType {
+      ///Feasible solution hasn't been found (but may exist).
+      UNDEFINED = 0,
+      ///The problem has no feasible solution
+      INFEASIBLE = 1,
+      ///Feasible solution found
+      FEASIBLE = 2,
+      ///Optimal solution exists and found
+      OPTIMAL = 3,
+      ///The cost function is unbounded
+      UNBOUNDED = 4
+    };
+
+    ///The basis status of variables
+    enum VarStatus {
+      /// The variable is in the basis
+      BASIC, 
+      /// The variable is free, but not basic
+      FREE,
+      /// The variable has active lower bound 
+      LOWER,
+      /// The variable has active upper bound
+      UPPER,
+      /// The variable is non-basic and fixed
+      FIXED
+    };
+
+  protected:
+
+    virtual SolveExitStatus _solve() = 0;
+
+    virtual Value _getPrimal(int i) const = 0;
+    virtual Value _getDual(int i) const = 0;
+
+    virtual Value _getPrimalRay(int i) const = 0;
+    virtual Value _getDualRay(int i) const = 0;
+
+    virtual Value _getPrimalValue() const = 0;
+
+    virtual VarStatus _getColStatus(int i) const = 0;
+    virtual VarStatus _getRowStatus(int i) const = 0;
+
+    virtual ProblemType _getPrimalType() const = 0;
+    virtual ProblemType _getDualType() const = 0;
+
+  public:
 
     ///\name Solve the LP
@@ -1327,6 +1831,4 @@
     ///values and their meanings can be found in the documentation of
     ///\ref SolveExitStatus.
-    ///
-    ///\todo Which method is used to solve the problem
     SolveExitStatus solve() { return _solve(); }
 
@@ -1337,47 +1839,92 @@
     ///@{
 
-    /// The status of the primal problem (the original LP problem)
-    SolutionStatus primalStatus() const {
-      return _getPrimalStatus();
-    }
-
-    /// The status of the dual (of the original LP) problem
-    SolutionStatus dualStatus() const {
-      return _getDualStatus();
-    }
-
-    ///The type of the original LP problem
-    ProblemTypes problemType() const {
-      return _getProblemType();
-    }
-
-    ///\e
-    Value primal(Col c) const { return _getPrimal(_lpId(c)); }
-    ///\e
+    /// The type of the primal problem
+    ProblemType primalType() const {
+      return _getPrimalType();
+    }
+
+    /// The type of the dual problem
+    ProblemType dualType() const {
+      return _getDualType();
+    }
+
+    /// Return the primal value of the column
+
+    /// Return the primal value of the column.
+    /// \pre The problem is solved.
+    Value primal(Col c) const { return _getPrimal(cols(id(c))); }
+
+    /// Return the primal value of the expression
+
+    /// Return the primal value of the expression, i.e. the dot
+    /// product of the primal solution and the expression.
+    /// \pre The problem is solved.
     Value primal(const Expr& e) const {
-      double res = e.constComp();
-      for (std::map<Col, double>::const_iterator it = e.begin();
-           it != e.end(); ++it) {
-        res += _getPrimal(_lpId(it->first)) * it->second;
+      double res = *e;
+      for (Expr::ConstCoeffIt c(e); c != INVALID; ++c) {
+        res += *c * primal(c);
       }
       return res;
     }
-
-    ///\e
-    Value dual(Row r) const { return _getDual(_lpId(r)); }
-    ///\e
+    /// Returns a component of the primal ray
+    
+    /// The primal ray is solution of the modified primal problem,
+    /// where we change each finite bound to 0, and we looking for a
+    /// negative objective value in case of minimization, and positive
+    /// objective value for maximization. If there is such solution,
+    /// that proofs the unsolvability of the dual problem, and if a
+    /// feasible primal solution exists, then the unboundness of
+    /// primal problem.
+    ///
+    /// \pre The problem is solved and the dual problem is infeasible.
+    /// \note Some solvers does not provide primal ray calculation
+    /// functions.
+    Value primalRay(Col c) const { return _getPrimalRay(cols(id(c))); }
+
+    /// Return the dual value of the row
+
+    /// Return the dual value of the row.
+    /// \pre The problem is solved.
+    Value dual(Row r) const { return _getDual(rows(id(r))); }
+
+    /// Return the dual value of the dual expression
+
+    /// Return the dual value of the dual expression, i.e. the dot
+    /// product of the dual solution and the dual expression.
+    /// \pre The problem is solved.
     Value dual(const DualExpr& e) const {
       double res = 0.0;
-      for (std::map<Row, double>::const_iterator it = e.begin();
-           it != e.end(); ++it) {
-        res += _getPrimal(_lpId(it->first)) * it->second;
+      for (DualExpr::ConstCoeffIt r(e); r != INVALID; ++r) {
+        res += *r * dual(r);
       }
       return res;
     }
 
-    ///\e
-    bool isBasicCol(Col c) const { return _isBasicCol(_lpId(c)); }
-
-    ///\e
+    /// Returns a component of the dual ray
+    
+    /// The dual ray is solution of the modified primal problem, where
+    /// we change each finite bound to 0 (i.e. the objective function
+    /// coefficients in the primal problem), and we looking for a
+    /// ositive objective value. If there is such solution, that
+    /// proofs the unsolvability of the primal problem, and if a
+    /// feasible dual solution exists, then the unboundness of
+    /// dual problem.
+    ///
+    /// \pre The problem is solved and the primal problem is infeasible.
+    /// \note Some solvers does not provide dual ray calculation
+    /// functions.
+    Value dualRay(Row r) const { return _getDualRay(rows(id(r))); }
+
+    /// Return the basis status of the column
+
+    /// \see VarStatus
+    VarStatus colStatus(Col c) const { return _getColStatus(cols(id(c))); }
+
+    /// Return the basis status of the row
+
+    /// \see VarStatus
+    VarStatus rowStatus(Row r) const { return _getRowStatus(rows(id(r))); }
+
+    ///The value of the objective function
 
     ///\return
@@ -1386,7 +1933,14 @@
     ///- \ref NaN if no primal solution is found.
     ///- The (finite) objective value if an optimal solution is found.
-    Value primalValue() const { return _getPrimalValue()+obj_const_comp;}
+    Value primal() const { return _getPrimalValue()+obj_const_comp;}
     ///@}
 
+    LpSolver* newSolver() {return _newSolver();}
+    LpSolver* cloneSolver() {return _cloneSolver();}
+
+  protected:
+
+    virtual LpSolver* _newSolver() const = 0;
+    virtual LpSolver* _cloneSolver() const = 0;
   };
 
@@ -1395,308 +1949,129 @@
   ///
   /// \brief Common base class for MIP solvers
-  /// \todo Much more docs
-  class MipSolverBase : virtual public LpSolverBase{
+  ///
+  /// This class is an abstract base class for MIP solvers. This class
+  /// provides a full interface for set and modify an MIP problem,
+  /// solve it and retrieve the solution. You can use one of the
+  /// descendants as a concrete implementation, or the \c Lp
+  /// default MIP solver. However, if you would like to handle MIP
+  /// solvers as reference or pointer in a generic way, you can use
+  /// this class directly.
+  class MipSolver : virtual public LpBase {
   public:
 
-    ///Possible variable (coloumn) types (e.g. real, integer, binary etc.)
+    /// The problem types for MIP problems
+    enum ProblemType {
+      ///Feasible solution hasn't been found (but may exist).
+      UNDEFINED = 0,
+      ///The problem has no feasible solution
+      INFEASIBLE = 1,
+      ///Feasible solution found
+      FEASIBLE = 2,
+      ///Optimal solution exists and found
+      OPTIMAL = 3,
+      ///The cost function is unbounded
+      ///
+      ///The Mip or at least the relaxed problem is unbounded
+      UNBOUNDED = 4
+    };
+
+    ///\name Solve the MIP
+
+    ///@{
+
+    /// Solve the MIP problem at hand
+    ///
+    ///\return The result of the optimization procedure. Possible
+    ///values and their meanings can be found in the documentation of
+    ///\ref SolveExitStatus.
+    SolveExitStatus solve() { return _solve(); }
+
+    ///@}
+
+    ///\name Setting column type
+    ///@{
+
+    ///Possible variable (column) types (e.g. real, integer, binary etc.)
     enum ColTypes {
-      ///Continuous variable
+      ///Continuous variable (default)
       REAL = 0,
       ///Integer variable
-
-      ///Unfortunately, cplex 7.5 somewhere writes something like
-      ///#define INTEGER 'I'
-      INT = 1
-      ///\todo No support for other types yet.
+      INTEGER = 1
     };
 
-    ///Sets the type of the given coloumn to the given type
-    ///
-    ///Sets the type of the given coloumn to the given type.
+    ///Sets the type of the given column to the given type
+
+    ///Sets the type of the given column to the given type.
+    ///
     void colType(Col c, ColTypes col_type) {
-      _colType(_lpId(c),col_type);
+      _setColType(cols(id(c)),col_type);
     }
 
     ///Gives back the type of the column.
-    ///
+
     ///Gives back the type of the column.
+    ///
     ColTypes colType(Col c) const {
-      return _colType(_lpId(c));
-    }
-
-    ///Sets the type of the given Col to integer or remove that property.
-    ///
-    ///Sets the type of the given Col to integer or remove that property.
-    void integer(Col c, bool enable) {
-      if (enable)
-        colType(c,INT);
-      else
-        colType(c,REAL);
-    }
-
-    ///Gives back whether the type of the column is integer or not.
-    ///
-    ///Gives back the type of the column.
-    ///\return true if the column has integer type and false if not.
-    bool integer(Col c) const {
-      return (colType(c)==INT);
-    }
-
-    /// The status of the MIP problem
-    SolutionStatus mipStatus() const {
-      return _getMipStatus();
-    }
+      return _getColType(cols(id(c)));
+    }
+    ///@}
+
+    ///\name Obtain the solution
+
+    ///@{
+
+    /// The type of the MIP problem
+    ProblemType type() const {
+      return _getType();
+    }
+
+    /// Return the value of the row in the solution
+
+    ///  Return the value of the row in the solution.
+    /// \pre The problem is solved.
+    Value sol(Col c) const { return _getSol(cols(id(c))); }
+
+    /// Return the value of the expression in the solution
+
+    /// Return the value of the expression in the solution, i.e. the
+    /// dot product of the solution and the expression.
+    /// \pre The problem is solved.
+    Value sol(const Expr& e) const {
+      double res = *e;
+      for (Expr::ConstCoeffIt c(e); c != INVALID; ++c) {
+        res += *c * sol(c);
+      }
+      return res;
+    }
+    ///The value of the objective function
+    
+    ///\return
+    ///- \ref INF or -\ref INF means either infeasibility or unboundedness
+    /// of the problem, depending on whether we minimize or maximize.
+    ///- \ref NaN if no primal solution is found.
+    ///- The (finite) objective value if an optimal solution is found.
+    Value solValue() const { return _getSolValue()+obj_const_comp;}
+    ///@}
 
   protected:
 
-    virtual ColTypes _colType(int col) const = 0;
-    virtual void _colType(int col, ColTypes col_type) = 0;
-    virtual SolutionStatus _getMipStatus() const = 0;
-
+    virtual SolveExitStatus _solve() = 0;
+    virtual ColTypes _getColType(int col) const = 0;
+    virtual void _setColType(int col, ColTypes col_type) = 0;
+    virtual ProblemType _getType() const = 0;
+    virtual Value _getSol(int i) const = 0;
+    virtual Value _getSolValue() const = 0;
+
+  public:
+
+    MipSolver* newSolver() {return _newSolver();}
+    MipSolver* cloneSolver() {return _cloneSolver();}
+
+  protected:
+
+    virtual MipSolver* _newSolver() const = 0;
+    virtual MipSolver* _cloneSolver() const = 0;
   };
 
-  ///\relates LpSolverBase::Expr
-  ///
-  inline LpSolverBase::Expr operator+(const LpSolverBase::Expr &a,
-                                      const LpSolverBase::Expr &b)
-  {
-    LpSolverBase::Expr tmp(a);
-    tmp+=b;
-    return tmp;
-  }
-  ///\e
-
-  ///\relates LpSolverBase::Expr
-  ///
-  inline LpSolverBase::Expr operator-(const LpSolverBase::Expr &a,
-                                      const LpSolverBase::Expr &b)
-  {
-    LpSolverBase::Expr tmp(a);
-    tmp-=b;
-    return tmp;
-  }
-  ///\e
-
-  ///\relates LpSolverBase::Expr
-  ///
-  inline LpSolverBase::Expr operator*(const LpSolverBase::Expr &a,
-                                      const LpSolverBase::Value &b)
-  {
-    LpSolverBase::Expr tmp(a);
-    tmp*=b;
-    return tmp;
-  }
-
-  ///\e
-
-  ///\relates LpSolverBase::Expr
-  ///
-  inline LpSolverBase::Expr operator*(const LpSolverBase::Value &a,
-                                      const LpSolverBase::Expr &b)
-  {
-    LpSolverBase::Expr tmp(b);
-    tmp*=a;
-    return tmp;
-  }
-  ///\e
-
-  ///\relates LpSolverBase::Expr
-  ///
-  inline LpSolverBase::Expr operator/(const LpSolverBase::Expr &a,
-                                      const LpSolverBase::Value &b)
-  {
-    LpSolverBase::Expr tmp(a);
-    tmp/=b;
-    return tmp;
-  }
-
-  ///\e
-
-  ///\relates LpSolverBase::Constr
-  ///
-  inline LpSolverBase::Constr operator<=(const LpSolverBase::Expr &e,
-                                         const LpSolverBase::Expr &f)
-  {
-    return LpSolverBase::Constr(-LpSolverBase::INF,e-f,0);
-  }
-
-  ///\e
-
-  ///\relates LpSolverBase::Constr
-  ///
-  inline LpSolverBase::Constr operator<=(const LpSolverBase::Value &e,
-                                         const LpSolverBase::Expr &f)
-  {
-    return LpSolverBase::Constr(e,f);
-  }
-
-  ///\e
-
-  ///\relates LpSolverBase::Constr
-  ///
-  inline LpSolverBase::Constr operator<=(const LpSolverBase::Expr &e,
-                                         const LpSolverBase::Value &f)
-  {
-    return LpSolverBase::Constr(-LpSolverBase::INF,e,f);
-  }
-
-  ///\e
-
-  ///\relates LpSolverBase::Constr
-  ///
-  inline LpSolverBase::Constr operator>=(const LpSolverBase::Expr &e,
-                                         const LpSolverBase::Expr &f)
-  {
-    return LpSolverBase::Constr(-LpSolverBase::INF,f-e,0);
-  }
-
-
-  ///\e
-
-  ///\relates LpSolverBase::Constr
-  ///
-  inline LpSolverBase::Constr operator>=(const LpSolverBase::Value &e,
-                                         const LpSolverBase::Expr &f)
-  {
-    return LpSolverBase::Constr(f,e);
-  }
-
-
-  ///\e
-
-  ///\relates LpSolverBase::Constr
-  ///
-  inline LpSolverBase::Constr operator>=(const LpSolverBase::Expr &e,
-                                         const LpSolverBase::Value &f)
-  {
-    return LpSolverBase::Constr(f,e,LpSolverBase::INF);
-  }
-
-  ///\e
-
-  ///\relates LpSolverBase::Constr
-  ///
-  inline LpSolverBase::Constr operator==(const LpSolverBase::Expr &e,
-                                         const LpSolverBase::Value &f)
-  {
-    return LpSolverBase::Constr(f,e,f);
-  }
-
-  ///\e
-
-  ///\relates LpSolverBase::Constr
-  ///
-  inline LpSolverBase::Constr operator==(const LpSolverBase::Expr &e,
-                                         const LpSolverBase::Expr &f)
-  {
-    return LpSolverBase::Constr(0,e-f,0);
-  }
-
-  ///\e
-
-  ///\relates LpSolverBase::Constr
-  ///
-  inline LpSolverBase::Constr operator<=(const LpSolverBase::Value &n,
-                                         const LpSolverBase::Constr&c)
-  {
-    LpSolverBase::Constr tmp(c);
-    LEMON_ASSERT(LpSolverBase::isNaN(tmp.lowerBound()), "Wrong LP constraint");
-    tmp.lowerBound()=n;
-    return tmp;
-  }
-  ///\e
-
-  ///\relates LpSolverBase::Constr
-  ///
-  inline LpSolverBase::Constr operator<=(const LpSolverBase::Constr& c,
-                                         const LpSolverBase::Value &n)
-  {
-    LpSolverBase::Constr tmp(c);
-    LEMON_ASSERT(LpSolverBase::isNaN(tmp.upperBound()), "Wrong LP constraint");
-    tmp.upperBound()=n;
-    return tmp;
-  }
-
-  ///\e
-
-  ///\relates LpSolverBase::Constr
-  ///
-  inline LpSolverBase::Constr operator>=(const LpSolverBase::Value &n,
-                                         const LpSolverBase::Constr&c)
-  {
-    LpSolverBase::Constr tmp(c);
-    LEMON_ASSERT(LpSolverBase::isNaN(tmp.upperBound()), "Wrong LP constraint");
-    tmp.upperBound()=n;
-    return tmp;
-  }
-  ///\e
-
-  ///\relates LpSolverBase::Constr
-  ///
-  inline LpSolverBase::Constr operator>=(const LpSolverBase::Constr& c,
-                                         const LpSolverBase::Value &n)
-  {
-    LpSolverBase::Constr tmp(c);
-    LEMON_ASSERT(LpSolverBase::isNaN(tmp.lowerBound()), "Wrong LP constraint");
-    tmp.lowerBound()=n;
-    return tmp;
-  }
-
-  ///\e
-
-  ///\relates LpSolverBase::DualExpr
-  ///
-  inline LpSolverBase::DualExpr operator+(const LpSolverBase::DualExpr &a,
-                                          const LpSolverBase::DualExpr &b)
-  {
-    LpSolverBase::DualExpr tmp(a);
-    tmp+=b;
-    return tmp;
-  }
-  ///\e
-
-  ///\relates LpSolverBase::DualExpr
-  ///
-  inline LpSolverBase::DualExpr operator-(const LpSolverBase::DualExpr &a,
-                                          const LpSolverBase::DualExpr &b)
-  {
-    LpSolverBase::DualExpr tmp(a);
-    tmp-=b;
-    return tmp;
-  }
-  ///\e
-
-  ///\relates LpSolverBase::DualExpr
-  ///
-  inline LpSolverBase::DualExpr operator*(const LpSolverBase::DualExpr &a,
-                                          const LpSolverBase::Value &b)
-  {
-    LpSolverBase::DualExpr tmp(a);
-    tmp*=b;
-    return tmp;
-  }
-
-  ///\e
-
-  ///\relates LpSolverBase::DualExpr
-  ///
-  inline LpSolverBase::DualExpr operator*(const LpSolverBase::Value &a,
-                                          const LpSolverBase::DualExpr &b)
-  {
-    LpSolverBase::DualExpr tmp(b);
-    tmp*=a;
-    return tmp;
-  }
-  ///\e
-
-  ///\relates LpSolverBase::DualExpr
-  ///
-  inline LpSolverBase::DualExpr operator/(const LpSolverBase::DualExpr &a,
-                                          const LpSolverBase::Value &b)
-  {
-    LpSolverBase::DualExpr tmp(a);
-    tmp/=b;
-    return tmp;
-  }
 
 
Index: lemon/lp_clp.cc
===================================================================
--- lemon/lp_clp.cc	(revision 459)
+++ lemon/lp_clp.cc	(revision 459)
@@ -0,0 +1,437 @@
+/* -*- mode: C++; indent-tabs-mode: nil; -*-
+ *
+ * This file is a part of LEMON, a generic C++ optimization library.
+ *
+ * Copyright (C) 2003-2008
+ * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
+ * (Egervary Research Group on Combinatorial Optimization, EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ */
+
+#include <lemon/lp_clp.h>
+#include <coin/ClpSimplex.hpp>
+
+namespace lemon {
+
+  LpClp::LpClp() {
+    _prob = new ClpSimplex();
+    _init_temporals();
+    messageLevel(MESSAGE_NO_OUTPUT);
+  }
+
+  LpClp::LpClp(const LpClp& other) {
+    _prob = new ClpSimplex(*other._prob);
+    rows = other.rows;
+    cols = other.cols;
+    _init_temporals();
+    messageLevel(MESSAGE_NO_OUTPUT);
+  }
+
+  LpClp::~LpClp() {
+    delete _prob;
+    _clear_temporals();
+  }
+
+  void LpClp::_init_temporals() {
+    _primal_ray = 0;
+    _dual_ray = 0;
+  }
+
+  void LpClp::_clear_temporals() {
+    if (_primal_ray) {
+      delete[] _primal_ray;
+      _primal_ray = 0;
+    }
+    if (_dual_ray) {
+      delete[] _dual_ray;
+      _dual_ray = 0;
+    }
+  }
+
+  LpClp* LpClp::_newSolver() const {
+    LpClp* newlp = new LpClp;
+    return newlp;
+  }
+
+  LpClp* LpClp::_cloneSolver() const {
+    LpClp* copylp = new LpClp(*this);
+    return copylp;
+  }
+
+  const char* LpClp::_solverName() const { return "LpClp"; }
+
+  int LpClp::_addCol() {
+    _prob->addColumn(0, 0, 0, -COIN_DBL_MAX, COIN_DBL_MAX, 0.0);
+    return _prob->numberColumns() - 1;
+  }
+
+  int LpClp::_addRow() {
+    _prob->addRow(0, 0, 0, -COIN_DBL_MAX, COIN_DBL_MAX);
+    return _prob->numberRows() - 1;
+  }
+
+
+  void LpClp::_eraseCol(int c) {
+    _col_names_ref.erase(_prob->getColumnName(c));
+    _prob->deleteColumns(1, &c);
+  }
+
+  void LpClp::_eraseRow(int r) {
+    _row_names_ref.erase(_prob->getRowName(r));
+    _prob->deleteRows(1, &r);
+  }
+
+  void LpClp::_eraseColId(int i) {
+    cols.eraseIndex(i);
+    cols.shiftIndices(i);
+  }
+
+  void LpClp::_eraseRowId(int i) {
+    rows.eraseIndex(i);
+    rows.shiftIndices(i);
+  }
+
+  void LpClp::_getColName(int c, std::string& name) const {
+    name = _prob->getColumnName(c);
+  }
+
+  void LpClp::_setColName(int c, const std::string& name) {
+    _prob->setColumnName(c, const_cast<std::string&>(name));
+    _col_names_ref[name] = c;
+  }
+
+  int LpClp::_colByName(const std::string& name) const {
+    std::map<std::string, int>::const_iterator it = _col_names_ref.find(name);
+    return it != _col_names_ref.end() ? it->second : -1;
+  }
+
+  void LpClp::_getRowName(int r, std::string& name) const {
+    name = _prob->getRowName(r);
+  }
+
+  void LpClp::_setRowName(int r, const std::string& name) {
+    _prob->setRowName(r, const_cast<std::string&>(name));
+    _row_names_ref[name] = r;
+  }
+
+  int LpClp::_rowByName(const std::string& name) const {
+    std::map<std::string, int>::const_iterator it = _row_names_ref.find(name);
+    return it != _row_names_ref.end() ? it->second : -1;
+  }
+
+
+  void LpClp::_setRowCoeffs(int ix, ExprIterator b, ExprIterator e) {
+    std::map<int, Value> coeffs;
+
+    int n = _prob->clpMatrix()->getNumCols();
+
+    const int* indices = _prob->clpMatrix()->getIndices();
+    const double* elements = _prob->clpMatrix()->getElements();
+
+    for (int i = 0; i < n; ++i) {
+      CoinBigIndex begin = _prob->clpMatrix()->getVectorStarts()[i];
+      CoinBigIndex end = begin + _prob->clpMatrix()->getVectorLengths()[i];
+
+      const int* it = std::lower_bound(indices + begin, indices + end, ix);
+      if (it != indices + end && *it == ix && elements[it - indices] != 0.0) {
+        coeffs[i] = 0.0;
+      }
+    }
+
+    for (ExprIterator it = b; it != e; ++it) {
+      coeffs[it->first] = it->second;
+    }
+
+    for (std::map<int, Value>::iterator it = coeffs.begin();
+         it != coeffs.end(); ++it) {
+      _prob->modifyCoefficient(ix, it->first, it->second);
+    }
+  }
+
+  void LpClp::_getRowCoeffs(int ix, InsertIterator b) const {
+    int n = _prob->clpMatrix()->getNumCols();
+
+    const int* indices = _prob->clpMatrix()->getIndices();
+    const double* elements = _prob->clpMatrix()->getElements();
+
+    for (int i = 0; i < n; ++i) {
+      CoinBigIndex begin = _prob->clpMatrix()->getVectorStarts()[i];
+      CoinBigIndex end = begin + _prob->clpMatrix()->getVectorLengths()[i];
+
+      const int* it = std::lower_bound(indices + begin, indices + end, ix);
+      if (it != indices + end && *it == ix) {
+        *b = std::make_pair(i, elements[it - indices]);
+      }
+    }
+  }
+
+  void LpClp::_setColCoeffs(int ix, ExprIterator b, ExprIterator e) {
+    std::map<int, Value> coeffs;
+
+    CoinBigIndex begin = _prob->clpMatrix()->getVectorStarts()[ix];
+    CoinBigIndex end = begin + _prob->clpMatrix()->getVectorLengths()[ix];
+
+    const int* indices = _prob->clpMatrix()->getIndices();
+    const double* elements = _prob->clpMatrix()->getElements();
+
+    for (CoinBigIndex i = begin; i != end; ++i) {
+      if (elements[i] != 0.0) {
+        coeffs[indices[i]] = 0.0;
+      }
+    }
+    for (ExprIterator it = b; it != e; ++it) {
+      coeffs[it->first] = it->second;
+    }
+    for (std::map<int, Value>::iterator it = coeffs.begin();
+         it != coeffs.end(); ++it) {
+      _prob->modifyCoefficient(it->first, ix, it->second);
+    }
+  }
+
+  void LpClp::_getColCoeffs(int ix, InsertIterator b) const {
+    CoinBigIndex begin = _prob->clpMatrix()->getVectorStarts()[ix];
+    CoinBigIndex end = begin + _prob->clpMatrix()->getVectorLengths()[ix];
+
+    const int* indices = _prob->clpMatrix()->getIndices();
+    const double* elements = _prob->clpMatrix()->getElements();
+
+    for (CoinBigIndex i = begin; i != end; ++i) {
+      *b = std::make_pair(indices[i], elements[i]);
+      ++b;
+    }
+  }
+
+  void LpClp::_setCoeff(int ix, int jx, Value value) {
+    _prob->modifyCoefficient(ix, jx, value);
+  }
+
+  LpClp::Value LpClp::_getCoeff(int ix, int jx) const {
+    CoinBigIndex begin = _prob->clpMatrix()->getVectorStarts()[ix];
+    CoinBigIndex end = begin + _prob->clpMatrix()->getVectorLengths()[ix];
+
+    const int* indices = _prob->clpMatrix()->getIndices();
+    const double* elements = _prob->clpMatrix()->getElements();
+
+    const int* it = std::lower_bound(indices + begin, indices + end, jx);
+    if (it != indices + end && *it == jx) {
+      return elements[it - indices];
+    } else {
+      return 0.0;
+    }
+  }
+
+  void LpClp::_setColLowerBound(int i, Value lo) {
+    _prob->setColumnLower(i, lo == - INF ? - COIN_DBL_MAX : lo);
+  }
+
+  LpClp::Value LpClp::_getColLowerBound(int i) const {
+    double val = _prob->getColLower()[i];
+    return val == - COIN_DBL_MAX ? - INF : val;
+  }
+
+  void LpClp::_setColUpperBound(int i, Value up) {
+    _prob->setColumnUpper(i, up == INF ? COIN_DBL_MAX : up);
+  }
+
+  LpClp::Value LpClp::_getColUpperBound(int i) const {
+    double val = _prob->getColUpper()[i];
+    return val == COIN_DBL_MAX ? INF : val;
+  }
+
+  void LpClp::_setRowLowerBound(int i, Value lo) {
+    _prob->setRowLower(i, lo == - INF ? - COIN_DBL_MAX : lo);
+  }
+
+  LpClp::Value LpClp::_getRowLowerBound(int i) const {
+    double val = _prob->getRowLower()[i];
+    return val == - COIN_DBL_MAX ? - INF : val;
+  }
+
+  void LpClp::_setRowUpperBound(int i, Value up) {
+    _prob->setRowUpper(i, up == INF ? COIN_DBL_MAX : up);
+  }
+
+  LpClp::Value LpClp::_getRowUpperBound(int i) const {
+    double val = _prob->getRowUpper()[i];
+    return val == COIN_DBL_MAX ? INF : val;
+  }
+
+  void LpClp::_setObjCoeffs(ExprIterator b, ExprIterator e) {
+    int num = _prob->clpMatrix()->getNumCols();
+    for (int i = 0; i < num; ++i) {
+      _prob->setObjectiveCoefficient(i, 0.0);
+    }
+    for (ExprIterator it = b; it != e; ++it) {
+      _prob->setObjectiveCoefficient(it->first, it->second);
+    }
+  }
+
+  void LpClp::_getObjCoeffs(InsertIterator b) const {
+    int num = _prob->clpMatrix()->getNumCols();
+    for (int i = 0; i < num; ++i) {
+      Value coef = _prob->getObjCoefficients()[i];
+      if (coef != 0.0) {
+        *b = std::make_pair(i, coef);
+        ++b;
+      }
+    }
+  }
+
+  void LpClp::_setObjCoeff(int i, Value obj_coef) {
+    _prob->setObjectiveCoefficient(i, obj_coef);
+  }
+
+  LpClp::Value LpClp::_getObjCoeff(int i) const {
+    return _prob->getObjCoefficients()[i];
+  }
+
+  LpClp::SolveExitStatus LpClp::_solve() {
+    return _prob->primal() >= 0 ? SOLVED : UNSOLVED;
+  }
+
+  LpClp::SolveExitStatus LpClp::solvePrimal() {
+    return _prob->primal() >= 0 ? SOLVED : UNSOLVED;
+  }
+
+  LpClp::SolveExitStatus LpClp::solveDual() {
+    return _prob->dual() >= 0 ? SOLVED : UNSOLVED;
+  }
+
+  LpClp::SolveExitStatus LpClp::solveBarrier() {
+    return _prob->barrier() >= 0 ? SOLVED : UNSOLVED;
+  }
+
+  LpClp::Value LpClp::_getPrimal(int i) const {
+    return _prob->primalColumnSolution()[i];
+  }
+  LpClp::Value LpClp::_getPrimalValue() const {
+    return _prob->objectiveValue();
+  }
+
+  LpClp::Value LpClp::_getDual(int i) const {
+    return _prob->dualRowSolution()[i];
+  }
+
+  LpClp::Value LpClp::_getPrimalRay(int i) const {
+    if (!_primal_ray) {
+      _primal_ray = _prob->unboundedRay();
+      LEMON_ASSERT(_primal_ray != 0, "Primal ray is not provided");
+    }
+    return _primal_ray[i];
+  }
+
+  LpClp::Value LpClp::_getDualRay(int i) const {
+    if (!_dual_ray) {
+      _dual_ray = _prob->infeasibilityRay();
+      LEMON_ASSERT(_dual_ray != 0, "Dual ray is not provided");
+    }
+    return _dual_ray[i];
+  }
+
+  LpClp::VarStatus LpClp::_getColStatus(int i) const {
+    switch (_prob->getColumnStatus(i)) {
+    case ClpSimplex::basic:
+      return BASIC;
+    case ClpSimplex::isFree:
+      return FREE;
+    case ClpSimplex::atUpperBound:
+      return UPPER;
+    case ClpSimplex::atLowerBound:
+      return LOWER;
+    case ClpSimplex::isFixed:
+      return FIXED;
+    case ClpSimplex::superBasic:
+      return FREE;
+    default:
+      LEMON_ASSERT(false, "Wrong column status");
+      return VarStatus();
+    }
+  }
+
+  LpClp::VarStatus LpClp::_getRowStatus(int i) const {
+    switch (_prob->getColumnStatus(i)) {
+    case ClpSimplex::basic:
+      return BASIC;
+    case ClpSimplex::isFree:
+      return FREE;
+    case ClpSimplex::atUpperBound:
+      return UPPER;
+    case ClpSimplex::atLowerBound:
+      return LOWER;
+    case ClpSimplex::isFixed:
+      return FIXED;
+    case ClpSimplex::superBasic:
+      return FREE;
+    default:
+      LEMON_ASSERT(false, "Wrong row status");
+      return VarStatus();
+    }
+  }
+
+
+  LpClp::ProblemType LpClp::_getPrimalType() const {
+    if (_prob->isProvenOptimal()) {
+      return OPTIMAL;
+    } else if (_prob->isProvenPrimalInfeasible()) {
+      return INFEASIBLE;
+    } else if (_prob->isProvenDualInfeasible()) {
+      return UNBOUNDED;
+    } else {
+      return UNDEFINED;
+    }
+  }
+
+  LpClp::ProblemType LpClp::_getDualType() const {
+    if (_prob->isProvenOptimal()) {
+      return OPTIMAL;
+    } else if (_prob->isProvenDualInfeasible()) {
+      return INFEASIBLE;
+    } else if (_prob->isProvenPrimalInfeasible()) {
+      return INFEASIBLE;
+    } else {
+      return UNDEFINED;
+    }
+  }
+
+  void LpClp::_setSense(LpClp::Sense sense) {
+    switch (sense) {
+    case MIN:
+      _prob->setOptimizationDirection(1);
+      break;
+    case MAX:
+      _prob->setOptimizationDirection(-1);
+      break;
+    }
+  }
+
+  LpClp::Sense LpClp::_getSense() const {
+    double dir = _prob->optimizationDirection();
+    if (dir > 0.0) {
+      return MIN;
+    } else {
+      return MAX;
+    }
+  }
+
+  void LpClp::_clear() {
+    delete _prob;
+    _prob = new ClpSimplex();
+    rows.clear();
+    cols.clear();
+    _col_names_ref.clear();
+    _clear_temporals();
+  }
+
+  void LpClp::messageLevel(MessageLevel m) {
+    _prob->setLogLevel(static_cast<int>(m));
+  }
+
+} //END OF NAMESPACE LEMON
Index: lemon/lp_clp.h
===================================================================
--- lemon/lp_clp.h	(revision 459)
+++ lemon/lp_clp.h	(revision 459)
@@ -0,0 +1,179 @@
+/* -*- mode: C++; indent-tabs-mode: nil; -*-
+ *
+ * This file is a part of LEMON, a generic C++ optimization library.
+ *
+ * Copyright (C) 2003-2008
+ * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
+ * (Egervary Research Group on Combinatorial Optimization, EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ */
+
+#ifndef LEMON_LP_CLP_H
+#define LEMON_LP_CLP_H
+
+///\file
+///\brief Header of the LEMON-CLP lp solver interface.
+
+#include <vector>
+#include <string>
+
+#include <lemon/lp_base.h>
+
+class ClpSimplex;
+
+namespace lemon {
+
+  /// \ingroup lp_group
+  ///
+  /// \brief Interface for the CLP solver
+  ///
+  /// This class implements an interface for the Clp LP solver.  The
+  /// Clp library is an object oriented lp solver library developed at
+  /// the IBM. The CLP is part of the COIN-OR package and it can be
+  /// used with Common Public License.
+  class LpClp : public LpSolver {
+  protected:
+
+    ClpSimplex* _prob;
+
+    std::map<std::string, int> _col_names_ref;
+    std::map<std::string, int> _row_names_ref;
+
+  public:
+
+    /// \e
+    LpClp();
+    /// \e
+    LpClp(const LpClp&);
+    /// \e
+    ~LpClp();
+
+  protected:
+
+    mutable double* _primal_ray;
+    mutable double* _dual_ray;
+
+    void _init_temporals();
+    void _clear_temporals();
+
+  protected:
+
+    virtual LpClp* _newSolver() const;
+    virtual LpClp* _cloneSolver() const;
+
+    virtual const char* _solverName() const;
+
+    virtual int _addCol();
+    virtual int _addRow();
+
+    virtual void _eraseCol(int i);
+    virtual void _eraseRow(int i);
+
+    virtual void _eraseColId(int i);
+    virtual void _eraseRowId(int i);
+
+    virtual void _getColName(int col, std::string& name) const;
+    virtual void _setColName(int col, const std::string& name);
+    virtual int _colByName(const std::string& name) const;
+
+    virtual void _getRowName(int row, std::string& name) const;
+    virtual void _setRowName(int row, const std::string& name);
+    virtual int _rowByName(const std::string& name) const;
+
+    virtual void _setRowCoeffs(int i, ExprIterator b, ExprIterator e);
+    virtual void _getRowCoeffs(int i, InsertIterator b) const;
+
+    virtual void _setColCoeffs(int i, ExprIterator b, ExprIterator e);
+    virtual void _getColCoeffs(int i, InsertIterator b) const;
+
+    virtual void _setCoeff(int row, int col, Value value);
+    virtual Value _getCoeff(int row, int col) const;
+
+    virtual void _setColLowerBound(int i, Value value);
+    virtual Value _getColLowerBound(int i) const;
+    virtual void _setColUpperBound(int i, Value value);
+    virtual Value _getColUpperBound(int i) const;
+
+    virtual void _setRowLowerBound(int i, Value value);
+    virtual Value _getRowLowerBound(int i) const;
+    virtual void _setRowUpperBound(int i, Value value);
+    virtual Value _getRowUpperBound(int i) const;
+
+    virtual void _setObjCoeffs(ExprIterator, ExprIterator);
+    virtual void _getObjCoeffs(InsertIterator) const;
+
+    virtual void _setObjCoeff(int i, Value obj_coef);
+    virtual Value _getObjCoeff(int i) const;
+
+    virtual void _setSense(Sense sense);
+    virtual Sense _getSense() const;
+
+    virtual SolveExitStatus _solve();
+
+    virtual Value _getPrimal(int i) const;
+    virtual Value _getDual(int i) const;
+
+    virtual Value _getPrimalValue() const;
+
+    virtual Value _getPrimalRay(int i) const;
+    virtual Value _getDualRay(int i) const;
+
+    virtual VarStatus _getColStatus(int i) const;
+    virtual VarStatus _getRowStatus(int i) const;
+
+    virtual ProblemType _getPrimalType() const;
+    virtual ProblemType _getDualType() const;
+
+    virtual void _clear();
+
+  public:
+
+    ///Solves LP with primal simplex method.
+    SolveExitStatus solvePrimal();
+
+    ///Solves LP with dual simplex method.
+    SolveExitStatus solveDual();
+
+    ///Solves LP with barrier method.
+    SolveExitStatus solveBarrier();
+
+    ///Returns the constraint identifier understood by CLP.
+    int clpRow(Row r) const { return rows(id(r)); }
+
+    ///Returns the variable identifier understood by CLP.
+    int clpCol(Col c) const { return cols(id(c)); }
+
+    ///Enum for \c messageLevel() parameter
+    enum MessageLevel {
+      /// no output (default value)
+      MESSAGE_NO_OUTPUT = 0,
+      /// print final solution
+      MESSAGE_FINAL_SOLUTION = 1,
+      /// print factorization
+      MESSAGE_FACTORIZATION = 2,
+      /// normal output
+      MESSAGE_NORMAL_OUTPUT = 3,
+      /// verbose output
+      MESSAGE_VERBOSE_OUTPUT = 4
+    };
+    ///Set the verbosity of the messages
+
+    ///Set the verbosity of the messages
+    ///
+    ///\param m is the level of the messages output by the solver routines.
+    void messageLevel(MessageLevel m);
+
+  };
+
+} //END OF NAMESPACE LEMON
+
+#endif //LEMON_LP_CLP_H
+
Index: lemon/lp_cplex.cc
===================================================================
--- lemon/lp_cplex.cc	(revision 458)
+++ lemon/lp_cplex.cc	(revision 459)
@@ -19,4 +19,6 @@
 #include <iostream>
 #include <vector>
+#include <cstring>
+
 #include <lemon/lp_cplex.h>
 
@@ -30,97 +32,125 @@
 namespace lemon {
 
-  LpCplex::LpCplex() {
-    //    env = CPXopenCPLEXdevelop(&status);
-    env = CPXopenCPLEX(&status);
-    lp = CPXcreateprob(env, &status, "LP problem");
-  }
-
-  LpCplex::LpCplex(const LpCplex& cplex) : LpSolverBase() {
-    env = CPXopenCPLEX(&status);
-    lp = CPXcloneprob(env, cplex.lp, &status);
+  CplexEnv::LicenseError::LicenseError(int status) {
+    if (!CPXgeterrorstring(0, status, _message)) {
+      std::strcpy(_message, "Cplex unknown error");
+    }
+  }
+
+  CplexEnv::CplexEnv() {
+    int status;
+    _cnt = new int;
+    _env = CPXopenCPLEX(&status);
+    if (_env == 0) {
+      delete _cnt;
+      _cnt = 0;
+      throw LicenseError(status);
+    }
+  }
+
+  CplexEnv::CplexEnv(const CplexEnv& other) {
+    _env = other._env;
+    _cnt = other._cnt;
+    ++(*_cnt);
+  }
+
+  CplexEnv& CplexEnv::operator=(const CplexEnv& other) {
+    _env = other._env;
+    _cnt = other._cnt;
+    ++(*_cnt);
+    return *this;
+  }
+
+  CplexEnv::~CplexEnv() {
+    --(*_cnt);
+    if (*_cnt == 0) {
+      delete _cnt;
+      CPXcloseCPLEX(&_env);
+    }
+  }
+
+  CplexBase::CplexBase() : LpBase() {
+    int status;
+    _prob = CPXcreateprob(cplexEnv(), &status, "Cplex problem");
+  }
+
+  CplexBase::CplexBase(const CplexEnv& env)
+    : LpBase(), _env(env) {
+    int status;
+    _prob = CPXcreateprob(cplexEnv(), &status, "Cplex problem");
+  }
+
+  CplexBase::CplexBase(const CplexBase& cplex)
+    : LpBase() {
+    int status;
+    _prob = CPXcloneprob(cplexEnv(), cplex._prob, &status);
     rows = cplex.rows;
     cols = cplex.cols;
   }
 
-  LpCplex::~LpCplex() {
-    CPXfreeprob(env,&lp);
-    CPXcloseCPLEX(&env);
-  }
-
-  LpSolverBase* LpCplex::_newLp()
-  {
-    //The first approach opens a new environment
-    return new LpCplex();
-  }
-
-  LpSolverBase* LpCplex::_copyLp() {
-    return new LpCplex(*this);
-  }
-
-  int LpCplex::_addCol()
-  {
-    int i = CPXgetnumcols(env, lp);
-    Value lb[1],ub[1];
-    lb[0]=-INF;
-    ub[0]=INF;
-    status = CPXnewcols(env, lp, 1, NULL, lb, ub, NULL, NULL);
+  CplexBase::~CplexBase() {
+    CPXfreeprob(cplexEnv(),&_prob);
+  }
+
+  int CplexBase::_addCol() {
+    int i = CPXgetnumcols(cplexEnv(), _prob);
+    double lb = -INF, ub = INF;
+    CPXnewcols(cplexEnv(), _prob, 1, 0, &lb, &ub, 0, 0);
     return i;
   }
 
 
-  int LpCplex::_addRow()
-  {
-    //We want a row that is not constrained
-    char sense[1];
-    sense[0]='L';//<= constraint
-    Value rhs[1];
-    rhs[0]=INF;
-    int i = CPXgetnumrows(env, lp);
-    status = CPXnewrows(env, lp, 1, rhs, sense, NULL, NULL);
+  int CplexBase::_addRow() {
+    int i = CPXgetnumrows(cplexEnv(), _prob);
+    const double ub = INF;
+    const char s = 'L';
+    CPXnewrows(cplexEnv(), _prob, 1, &ub, &s, 0, 0);
     return i;
   }
 
 
-  void LpCplex::_eraseCol(int i) {
-    CPXdelcols(env, lp, i, i);
-  }
-
-  void LpCplex::_eraseRow(int i) {
-    CPXdelrows(env, lp, i, i);
-  }
-
-  void LpCplex::_getColName(int col, std::string &name) const
-  {
-    ///\bug Untested
-    int storespace;
-    CPXgetcolname(env, lp, 0, 0, 0, &storespace, col, col);
-    if (storespace == 0) {
+  void CplexBase::_eraseCol(int i) {
+    CPXdelcols(cplexEnv(), _prob, i, i);
+  }
+
+  void CplexBase::_eraseRow(int i) {
+    CPXdelrows(cplexEnv(), _prob, i, i);
+  }
+
+  void CplexBase::_eraseColId(int i) {
+    cols.eraseIndex(i);
+    cols.shiftIndices(i);
+  }
+  void CplexBase::_eraseRowId(int i) {
+    rows.eraseIndex(i);
+    rows.shiftIndices(i);
+  }
+
+  void CplexBase::_getColName(int col, std::string &name) const {
+    int size;
+    CPXgetcolname(cplexEnv(), _prob, 0, 0, 0, &size, col, col);
+    if (size == 0) {
       name.clear();
       return;
     }
 
-    storespace *= -1;
-    std::vector<char> buf(storespace);
-    char *names[1];
-    int dontcare;
-    ///\bug return code unchecked for error
-    CPXgetcolname(env, lp, names, &*buf.begin(), storespace,
-                  &dontcare, col, col);
-    name = names[0];
-  }
-
-  void LpCplex::_setColName(int col, const std::string &name)
-  {
-    ///\bug Untested
-    char *names[1];
-    names[0] = const_cast<char*>(name.c_str());
-    ///\bug return code unchecked for error
-    CPXchgcolname(env, lp, 1, &col, names);
-  }
-
-  int LpCplex::_colByName(const std::string& name) const
-  {
+    size *= -1;
+    std::vector<char> buf(size);
+    char *cname;
+    int tmp;
+    CPXgetcolname(cplexEnv(), _prob, &cname, &buf.front(), size,
+                  &tmp, col, col);
+    name = cname;
+  }
+
+  void CplexBase::_setColName(int col, const std::string &name) {
+    char *cname;
+    cname = const_cast<char*>(name.c_str());
+    CPXchgcolname(cplexEnv(), _prob, 1, &col, &cname);
+  }
+
+  int CplexBase::_colByName(const std::string& name) const {
     int index;
-    if (CPXgetcolindex(env, lp,
+    if (CPXgetcolindex(cplexEnv(), _prob,
                        const_cast<char*>(name.c_str()), &index) == 0) {
       return index;
@@ -129,6 +159,38 @@
   }
 
-  ///\warning Data at index 0 is ignored in the arrays.
-  void LpCplex::_setRowCoeffs(int i, ConstRowIterator b, ConstRowIterator e)
+  void CplexBase::_getRowName(int row, std::string &name) const {
+    int size;
+    CPXgetrowname(cplexEnv(), _prob, 0, 0, 0, &size, row, row);
+    if (size == 0) {
+      name.clear();
+      return;
+    }
+
+    size *= -1;
+    std::vector<char> buf(size);
+    char *cname;
+    int tmp;
+    CPXgetrowname(cplexEnv(), _prob, &cname, &buf.front(), size,
+                  &tmp, row, row);
+    name = cname;
+  }
+
+  void CplexBase::_setRowName(int row, const std::string &name) {
+    char *cname;
+    cname = const_cast<char*>(name.c_str());
+    CPXchgrowname(cplexEnv(), _prob, 1, &row, &cname);
+  }
+
+  int CplexBase::_rowByName(const std::string& name) const {
+    int index;
+    if (CPXgetrowindex(cplexEnv(), _prob,
+                       const_cast<char*>(name.c_str()), &index) == 0) {
+      return index;
+    }
+    return -1;
+  }
+
+  void CplexBase::_setRowCoeffs(int i, ExprIterator b,
+                                      ExprIterator e)
   {
     std::vector<int> indices;
@@ -136,5 +198,5 @@
     std::vector<Value> values;
 
-    for(ConstRowIterator it=b; it!=e; ++it) {
+    for(ExprIterator it=b; it!=e; ++it) {
       indices.push_back(it->first);
       values.push_back(it->second);
@@ -142,11 +204,11 @@
     }
 
-    status = CPXchgcoeflist(env, lp, values.size(),
-                            &rowlist[0], &indices[0], &values[0]);
-  }
-
-  void LpCplex::_getRowCoeffs(int i, RowIterator b) const {
+    CPXchgcoeflist(cplexEnv(), _prob, values.size(),
+                   &rowlist.front(), &indices.front(), &values.front());
+  }
+
+  void CplexBase::_getRowCoeffs(int i, InsertIterator b) const {
     int tmp1, tmp2, tmp3, length;
-    CPXgetrows(env, lp, &tmp1, &tmp2, 0, 0, 0, &length, i, i);
+    CPXgetrows(cplexEnv(), _prob, &tmp1, &tmp2, 0, 0, 0, &length, i, i);
 
     length = -length;
@@ -154,5 +216,6 @@
     std::vector<double> values(length);
 
-    CPXgetrows(env, lp, &tmp1, &tmp2, &indices[0], &values[0],
+    CPXgetrows(cplexEnv(), _prob, &tmp1, &tmp2,
+               &indices.front(), &values.front(),
                length, &tmp3, i, i);
 
@@ -161,15 +224,12 @@
       ++b;
     }
-
-    /// \todo implement
-  }
-
-  void LpCplex::_setColCoeffs(int i, ConstColIterator b, ConstColIterator e)
-  {
+  }
+
+  void CplexBase::_setColCoeffs(int i, ExprIterator b, ExprIterator e) {
     std::vector<int> indices;
     std::vector<int> collist;
     std::vector<Value> values;
 
-    for(ConstColIterator it=b; it!=e; ++it) {
+    for(ExprIterator it=b; it!=e; ++it) {
       indices.push_back(it->first);
       values.push_back(it->second);
@@ -177,12 +237,12 @@
     }
 
-    status = CPXchgcoeflist(env, lp, values.size(),
-                            &indices[0], &collist[0], &values[0]);
-  }
-
-  void LpCplex::_getColCoeffs(int i, ColIterator b) const {
+    CPXchgcoeflist(cplexEnv(), _prob, values.size(),
+                   &indices.front(), &collist.front(), &values.front());
+  }
+
+  void CplexBase::_getColCoeffs(int i, InsertIterator b) const {
 
     int tmp1, tmp2, tmp3, length;
-    CPXgetcols(env, lp, &tmp1, &tmp2, 0, 0, 0, &length, i, i);
+    CPXgetcols(cplexEnv(), _prob, &tmp1, &tmp2, 0, 0, 0, &length, i, i);
 
     length = -length;
@@ -190,5 +250,6 @@
     std::vector<double> values(length);
 
-    CPXgetcols(env, lp, &tmp1, &tmp2, &indices[0], &values[0],
+    CPXgetcols(cplexEnv(), _prob, &tmp1, &tmp2,
+               &indices.front(), &values.front(),
                length, &tmp3, i, i);
 
@@ -200,173 +261,207 @@
   }
 
-  void LpCplex::_setCoeff(int row, int col, Value value)
+  void CplexBase::_setCoeff(int row, int col, Value value) {
+    CPXchgcoef(cplexEnv(), _prob, row, col, value);
+  }
+
+  CplexBase::Value CplexBase::_getCoeff(int row, int col) const {
+    CplexBase::Value value;
+    CPXgetcoef(cplexEnv(), _prob, row, col, &value);
+    return value;
+  }
+
+  void CplexBase::_setColLowerBound(int i, Value value) {
+    const char s = 'L';
+    CPXchgbds(cplexEnv(), _prob, 1, &i, &s, &value);
+  }
+
+  CplexBase::Value CplexBase::_getColLowerBound(int i) const {
+    CplexBase::Value res;
+    CPXgetlb(cplexEnv(), _prob, &res, i, i);
+    return res <= -CPX_INFBOUND ? -INF : res;
+  }
+
+  void CplexBase::_setColUpperBound(int i, Value value)
   {
-    CPXchgcoef(env, lp, row, col, value);
-  }
-
-  LpCplex::Value LpCplex::_getCoeff(int row, int col) const
+    const char s = 'U';
+    CPXchgbds(cplexEnv(), _prob, 1, &i, &s, &value);
+  }
+
+  CplexBase::Value CplexBase::_getColUpperBound(int i) const {
+    CplexBase::Value res;
+    CPXgetub(cplexEnv(), _prob, &res, i, i);
+    return res >= CPX_INFBOUND ? INF : res;
+  }
+
+  CplexBase::Value CplexBase::_getRowLowerBound(int i) const {
+    char s;
+    CPXgetsense(cplexEnv(), _prob, &s, i, i);
+    CplexBase::Value res;
+
+    switch (s) {
+    case 'G':
+    case 'R':
+    case 'E':
+      CPXgetrhs(cplexEnv(), _prob, &res, i, i);
+      return res <= -CPX_INFBOUND ? -INF : res;
+    default:
+      return -INF;
+    }
+  }
+
+  CplexBase::Value CplexBase::_getRowUpperBound(int i) const {
+    char s;
+    CPXgetsense(cplexEnv(), _prob, &s, i, i);
+    CplexBase::Value res;
+
+    switch (s) {
+    case 'L':
+    case 'E':
+      CPXgetrhs(cplexEnv(), _prob, &res, i, i);
+      return res >= CPX_INFBOUND ? INF : res;
+    case 'R':
+      CPXgetrhs(cplexEnv(), _prob, &res, i, i);
+      {
+        double rng;
+        CPXgetrngval(cplexEnv(), _prob, &rng, i, i);
+        res += rng;
+      }
+      return res >= CPX_INFBOUND ? INF : res;
+    default:
+      return INF;
+    }
+  }
+
+  //This is easier to implement
+  void CplexBase::_set_row_bounds(int i, Value lb, Value ub) {
+    if (lb == -INF) {
+      const char s = 'L';
+      CPXchgsense(cplexEnv(), _prob, 1, &i, &s);
+      CPXchgrhs(cplexEnv(), _prob, 1, &i, &ub);
+    } else if (ub == INF) {
+      const char s = 'G';
+      CPXchgsense(cplexEnv(), _prob, 1, &i, &s);
+      CPXchgrhs(cplexEnv(), _prob, 1, &i, &lb);
+    } else if (lb == ub){
+      const char s = 'E';
+      CPXchgsense(cplexEnv(), _prob, 1, &i, &s);
+      CPXchgrhs(cplexEnv(), _prob, 1, &i, &lb);
+    } else {
+      const char s = 'R';
+      CPXchgsense(cplexEnv(), _prob, 1, &i, &s);
+      CPXchgrhs(cplexEnv(), _prob, 1, &i, &lb);
+      double len = ub - lb;
+      CPXchgrngval(cplexEnv(), _prob, 1, &i, &len);
+    }
+  }
+
+  void CplexBase::_setRowLowerBound(int i, Value lb)
   {
-    LpCplex::Value value;
-    CPXgetcoef(env, lp, row, col, &value);
-    return value;
-  }
-
-  void LpCplex::_setColLowerBound(int i, Value value)
+    LEMON_ASSERT(lb != INF, "Invalid bound");
+    _set_row_bounds(i, lb, CplexBase::_getRowUpperBound(i));
+  }
+
+  void CplexBase::_setRowUpperBound(int i, Value ub)
   {
-    int indices[1];
-    indices[0]=i;
-    char lu[1];
-    lu[0]='L';
-    Value bd[1];
-    bd[0]=value;
-    status = CPXchgbds(env, lp, 1, indices, lu, bd);
-
-  }
-
-  LpCplex::Value LpCplex::_getColLowerBound(int i) const
+
+    LEMON_ASSERT(ub != -INF, "Invalid bound");
+    _set_row_bounds(i, CplexBase::_getRowLowerBound(i), ub);
+  }
+
+  void CplexBase::_setObjCoeffs(ExprIterator b, ExprIterator e)
   {
-    LpCplex::Value x;
-    CPXgetlb (env, lp, &x, i, i);
-    if (x <= -CPX_INFBOUND) x = -INF;
-    return x;
-  }
-
-  void LpCplex::_setColUpperBound(int i, Value value)
+    std::vector<int> indices;
+    std::vector<Value> values;
+    for(ExprIterator it=b; it!=e; ++it) {
+      indices.push_back(it->first);
+      values.push_back(it->second);
+    }
+    CPXchgobj(cplexEnv(), _prob, values.size(),
+              &indices.front(), &values.front());
+
+  }
+
+  void CplexBase::_getObjCoeffs(InsertIterator b) const
   {
-    int indices[1];
-    indices[0]=i;
-    char lu[1];
-    lu[0]='U';
-    Value bd[1];
-    bd[0]=value;
-    status = CPXchgbds(env, lp, 1, indices, lu, bd);
-  }
-
-  LpCplex::Value LpCplex::_getColUpperBound(int i) const
+    int num = CPXgetnumcols(cplexEnv(), _prob);
+    std::vector<Value> x(num);
+
+    CPXgetobj(cplexEnv(), _prob, &x.front(), 0, num - 1);
+    for (int i = 0; i < num; ++i) {
+      if (x[i] != 0.0) {
+        *b = std::make_pair(i, x[i]);
+        ++b;
+      }
+    }
+  }
+
+  void CplexBase::_setObjCoeff(int i, Value obj_coef)
   {
-    LpCplex::Value x;
-    CPXgetub (env, lp, &x, i, i);
-    if (x >= CPX_INFBOUND) x = INF;
-    return x;
-  }
-
-  //This will be easier to implement
-  void LpCplex::_setRowBounds(int i, Value lb, Value ub)
-  {
-    //Bad parameter
-    if (lb==INF || ub==-INF) {
-      //FIXME error
-    }
-
-    int cnt=1;
-    int indices[1];
-    indices[0]=i;
-    char sense[1];
-
-    if (lb==-INF){
-      sense[0]='L';
-      CPXchgsense(env, lp, cnt, indices, sense);
-      CPXchgcoef(env, lp, i, -1, ub);
-
-    }
-    else{
-      if (ub==INF){
-        sense[0]='G';
-        CPXchgsense(env, lp, cnt, indices, sense);
-        CPXchgcoef(env, lp, i, -1, lb);
-      }
-      else{
-        if (lb == ub){
-          sense[0]='E';
-          CPXchgsense(env, lp, cnt, indices, sense);
-          CPXchgcoef(env, lp, i, -1, lb);
-        }
-        else{
-          sense[0]='R';
-          CPXchgsense(env, lp, cnt, indices, sense);
-          CPXchgcoef(env, lp, i, -1, lb);
-          CPXchgcoef(env, lp, i, -2, ub-lb);
-        }
-      }
-    }
-  }
-
-//   void LpCplex::_setRowLowerBound(int i, Value value)
-//   {
-//     //Not implemented, obsolete
-//   }
-
-//   void LpCplex::_setRowUpperBound(int i, Value value)
-//   {
-//     //Not implemented, obsolete
-// //     //TODO Ezt kell meg megirni
-// //     //type of the problem
-// //     char sense[1];
-// //     status = CPXgetsense(env, lp, sense, i, i);
-// //     Value rhs[1];
-// //     status = CPXgetrhs(env, lp, rhs, i, i);
-
-// //     switch (sense[0]) {
-// //     case 'L'://<= constraint
-// //       break;
-// //     case 'E'://= constraint
-// //       break;
-// //     case 'G'://>= constraint
-// //       break;
-// //     case 'R'://ranged constraint
-// //       break;
-// //     default: ;
-// //       //FIXME error
-// //     }
-
-// //     status = CPXchgcoef(env, lp, i, -2, value_rng);
-//   }
-
-  void LpCplex::_getRowBounds(int i, Value &lb, Value &ub) const
-  {
-    char sense;
-    CPXgetsense(env, lp, &sense,i,i);
-    lb=-INF;
-    ub=INF;
-    switch (sense)
-      {
-      case 'L':
-        CPXgetcoef(env, lp, i, -1, &ub);
-        break;
-      case 'G':
-        CPXgetcoef(env, lp, i, -1, &lb);
-        break;
-      case 'E':
-        CPXgetcoef(env, lp, i, -1, &lb);
-        ub=lb;
-        break;
-      case 'R':
-        CPXgetcoef(env, lp, i, -1, &lb);
-        Value x;
-        CPXgetcoef(env, lp, i, -2, &x);
-        ub=lb+x;
-        break;
-      }
-  }
-
-  void LpCplex::_setObjCoeff(int i, Value obj_coef)
-  {
-    CPXchgcoef(env, lp, -1, i, obj_coef);
-  }
-
-  LpCplex::Value LpCplex::_getObjCoeff(int i) const
+    CPXchgobj(cplexEnv(), _prob, 1, &i, &obj_coef);
+  }
+
+  CplexBase::Value CplexBase::_getObjCoeff(int i) const
   {
     Value x;
-    CPXgetcoef(env, lp, -1, i, &x);
+    CPXgetobj(cplexEnv(), _prob, &x, i, i);
     return x;
   }
 
-  void LpCplex::_clearObj()
-  {
-    for (int i=0;i< CPXgetnumcols(env, lp);++i){
-      CPXchgcoef(env, lp, -1, i, 0);
-    }
-
-  }
+  void CplexBase::_setSense(CplexBase::Sense sense) {
+    switch (sense) {
+    case MIN:
+      CPXchgobjsen(cplexEnv(), _prob, CPX_MIN);
+      break;
+    case MAX:
+      CPXchgobjsen(cplexEnv(), _prob, CPX_MAX);
+      break;
+    }
+  }
+
+  CplexBase::Sense CplexBase::_getSense() const {
+    switch (CPXgetobjsen(cplexEnv(), _prob)) {
+    case CPX_MIN:
+      return MIN;
+    case CPX_MAX:
+      return MAX;
+    default:
+      LEMON_ASSERT(false, "Invalid sense");
+      return CplexBase::Sense();
+    }
+  }
+
+  void CplexBase::_clear() {
+    CPXfreeprob(cplexEnv(),&_prob);
+    int status;
+    _prob = CPXcreateprob(cplexEnv(), &status, "Cplex problem");
+    rows.clear();
+    cols.clear();
+  }
+
+  // LpCplex members
+
+  LpCplex::LpCplex()
+    : LpBase(), CplexBase(), LpSolver() {}
+
+  LpCplex::LpCplex(const CplexEnv& env)
+    : LpBase(), CplexBase(env), LpSolver() {}
+
+  LpCplex::LpCplex(const LpCplex& other)
+    : LpBase(), CplexBase(other), LpSolver() {}
+
+  LpCplex::~LpCplex() {}
+
+  LpCplex* LpCplex::_newSolver() const { return new LpCplex; }
+  LpCplex* LpCplex::_cloneSolver() const {return new LpCplex(*this); }
+
+  const char* LpCplex::_solverName() const { return "LpCplex"; }
+
+  void LpCplex::_clear_temporals() {
+    _col_status.clear();
+    _row_status.clear();
+    _primal_ray.clear();
+    _dual_ray.clear();
+  }
+
   // The routine returns zero unless an error occurred during the
   // optimization. Examples of errors include exhausting available
@@ -378,30 +473,22 @@
   // routines CPXsolninfo, CPXgetstat, and CPXsolution to obtain
   // further information about the status of the optimization.
-  LpCplex::SolveExitStatus LpCplex::_solve()
-  {
-    //CPX_PARAM_LPMETHOD
-    status = CPXlpopt(env, lp);
-    //status = CPXprimopt(env, lp);
+  LpCplex::SolveExitStatus LpCplex::convertStatus(int status) {
 #if CPX_VERSION >= 800
-    if (status)
-    {
+    if (status == 0) {
+      switch (CPXgetstat(cplexEnv(), _prob)) {
+      case CPX_STAT_OPTIMAL:
+      case CPX_STAT_INFEASIBLE:
+      case CPX_STAT_UNBOUNDED:
+        return SOLVED;
+      default:
+        return UNSOLVED;
+      }
+    } else {
       return UNSOLVED;
     }
-    else
-    {
-      switch (CPXgetstat(env, lp))
-      {
-        case CPX_STAT_OPTIMAL:
-        case CPX_STAT_INFEASIBLE:
-        case CPX_STAT_UNBOUNDED:
-          return SOLVED;
-        default:
-          return UNSOLVED;
-      }
-    }
 #else
-    if (status == 0){
+    if (status == 0) {
       //We want to exclude some cases
-      switch (CPXgetstat(env, lp)){
+      switch (CPXgetstat(cplexEnv(), _prob)) {
       case CPX_OBJ_LIM:
       case CPX_IT_LIM_FEAS:
@@ -413,6 +500,5 @@
         return SOLVED;
       }
-    }
-    else{
+    } else {
       return UNSOLVED;
     }
@@ -420,106 +506,171 @@
   }
 
-  LpCplex::Value LpCplex::_getPrimal(int i) const
-  {
+  LpCplex::SolveExitStatus LpCplex::_solve() {
+    _clear_temporals();
+    return convertStatus(CPXlpopt(cplexEnv(), _prob));
+  }
+
+  LpCplex::SolveExitStatus LpCplex::solvePrimal() {
+    _clear_temporals();
+    return convertStatus(CPXprimopt(cplexEnv(), _prob));
+  }
+
+  LpCplex::SolveExitStatus LpCplex::solveDual() {
+    _clear_temporals();
+    return convertStatus(CPXdualopt(cplexEnv(), _prob));
+  }
+
+  LpCplex::SolveExitStatus LpCplex::solveBarrier() {
+    _clear_temporals();
+    return convertStatus(CPXbaropt(cplexEnv(), _prob));
+  }
+
+  LpCplex::Value LpCplex::_getPrimal(int i) const {
     Value x;
-    CPXgetx(env, lp, &x, i, i);
+    CPXgetx(cplexEnv(), _prob, &x, i, i);
     return x;
   }
 
-  LpCplex::Value LpCplex::_getDual(int i) const
-  {
+  LpCplex::Value LpCplex::_getDual(int i) const {
     Value y;
-    CPXgetpi(env, lp, &y, i, i);
+    CPXgetpi(cplexEnv(), _prob, &y, i, i);
     return y;
   }
 
-  LpCplex::Value LpCplex::_getPrimalValue() const
-  {
+  LpCplex::Value LpCplex::_getPrimalValue() const {
     Value objval;
-    //method = CPXgetmethod (env, lp);
-    //printf("CPXgetprobtype %d \n",CPXgetprobtype(env,lp));
-    CPXgetobjval(env, lp, &objval);
-    //printf("Objective value: %g \n",objval);
+    CPXgetobjval(cplexEnv(), _prob, &objval);
     return objval;
   }
-  bool LpCplex::_isBasicCol(int i) const
-  {
-    std::vector<int> cstat(CPXgetnumcols(env, lp));
-    CPXgetbase(env, lp, &*cstat.begin(), NULL);
-    return (cstat[i]==CPX_BASIC);
-  }
-
-//7.5-os cplex statusai (Vigyazat: a 9.0-asei masok!)
-// This table lists the statuses, returned by the CPXgetstat()
-// routine, for solutions to LP problems or mixed integer problems. If
-// no solution exists, the return value is zero.
-
-// For Simplex, Barrier
-// 1          CPX_OPTIMAL
-//          Optimal solution found
-// 2          CPX_INFEASIBLE
-//          Problem infeasible
-// 3    CPX_UNBOUNDED
-//          Problem unbounded
-// 4          CPX_OBJ_LIM
-//          Objective limit exceeded in Phase II
-// 5          CPX_IT_LIM_FEAS
-//          Iteration limit exceeded in Phase II
-// 6          CPX_IT_LIM_INFEAS
-//          Iteration limit exceeded in Phase I
-// 7          CPX_TIME_LIM_FEAS
-//          Time limit exceeded in Phase II
-// 8          CPX_TIME_LIM_INFEAS
-//          Time limit exceeded in Phase I
-// 9          CPX_NUM_BEST_FEAS
-//          Problem non-optimal, singularities in Phase II
-// 10         CPX_NUM_BEST_INFEAS
-//          Problem non-optimal, singularities in Phase I
-// 11         CPX_OPTIMAL_INFEAS
-//          Optimal solution found, unscaled infeasibilities
-// 12         CPX_ABORT_FEAS
-//          Aborted in Phase II
-// 13         CPX_ABORT_INFEAS
-//          Aborted in Phase I
-// 14          CPX_ABORT_DUAL_INFEAS
-//          Aborted in barrier, dual infeasible
-// 15          CPX_ABORT_PRIM_INFEAS
-//          Aborted in barrier, primal infeasible
-// 16          CPX_ABORT_PRIM_DUAL_INFEAS
-//          Aborted in barrier, primal and dual infeasible
-// 17          CPX_ABORT_PRIM_DUAL_FEAS
-//          Aborted in barrier, primal and dual feasible
-// 18          CPX_ABORT_CROSSOVER
-//          Aborted in crossover
-// 19          CPX_INForUNBD
-//          Infeasible or unbounded
-// 20   CPX_PIVOT
-//       User pivot used
-//
-//     Ezeket hova tegyem:
-// ??case CPX_ABORT_DUAL_INFEAS
-// ??case CPX_ABORT_CROSSOVER
-// ??case CPX_INForUNBD
-// ??case CPX_PIVOT
-
-//Some more interesting stuff:
-
-// CPX_PARAM_LPMETHOD  1062  int  LPMETHOD
-// 0 Automatic
-// 1 Primal Simplex
-// 2 Dual Simplex
-// 3 Network Simplex
-// 4 Standard Barrier
-// Default: 0
-// Description: Method for linear optimization.
-// Determines which algorithm is used when CPXlpopt() (or "optimize"
-// in the Interactive Optimizer) is called. Currently the behavior of
-// the "Automatic" setting is that CPLEX simply invokes the dual
-// simplex method, but this capability may be expanded in the future
-// so that CPLEX chooses the method based on problem characteristics
+
+  LpCplex::VarStatus LpCplex::_getColStatus(int i) const {
+    if (_col_status.empty()) {
+      _col_status.resize(CPXgetnumcols(cplexEnv(), _prob));
+      CPXgetbase(cplexEnv(), _prob, &_col_status.front(), 0);
+    }
+    switch (_col_status[i]) {
+    case CPX_BASIC:
+      return BASIC;
+    case CPX_FREE_SUPER:
+      return FREE;
+    case CPX_AT_LOWER:
+      return LOWER;
+    case CPX_AT_UPPER:
+      return UPPER;
+    default:
+      LEMON_ASSERT(false, "Wrong column status");
+      return LpCplex::VarStatus();
+    }
+  }
+
+  LpCplex::VarStatus LpCplex::_getRowStatus(int i) const {
+    if (_row_status.empty()) {
+      _row_status.resize(CPXgetnumrows(cplexEnv(), _prob));
+      CPXgetbase(cplexEnv(), _prob, 0, &_row_status.front());
+    }
+    switch (_row_status[i]) {
+    case CPX_BASIC:
+      return BASIC;
+    case CPX_AT_LOWER:
+      {
+        char s;
+        CPXgetsense(cplexEnv(), _prob, &s, i, i);
+        return s != 'L' ? LOWER : UPPER;
+      }
+    case CPX_AT_UPPER:
+      return UPPER;
+    default:
+      LEMON_ASSERT(false, "Wrong row status");
+      return LpCplex::VarStatus();
+    }
+  }
+
+  LpCplex::Value LpCplex::_getPrimalRay(int i) const {
+    if (_primal_ray.empty()) {
+      _primal_ray.resize(CPXgetnumcols(cplexEnv(), _prob));
+      CPXgetray(cplexEnv(), _prob, &_primal_ray.front());
+    }
+    return _primal_ray[i];
+  }
+
+  LpCplex::Value LpCplex::_getDualRay(int i) const {
+    if (_dual_ray.empty()) {
+
+    }
+    return _dual_ray[i];
+  }
+
+  //7.5-os cplex statusai (Vigyazat: a 9.0-asei masok!)
+  // This table lists the statuses, returned by the CPXgetstat()
+  // routine, for solutions to LP problems or mixed integer problems. If
+  // no solution exists, the return value is zero.
+
+  // For Simplex, Barrier
+  // 1          CPX_OPTIMAL
+  //          Optimal solution found
+  // 2          CPX_INFEASIBLE
+  //          Problem infeasible
+  // 3    CPX_UNBOUNDED
+  //          Problem unbounded
+  // 4          CPX_OBJ_LIM
+  //          Objective limit exceeded in Phase II
+  // 5          CPX_IT_LIM_FEAS
+  //          Iteration limit exceeded in Phase II
+  // 6          CPX_IT_LIM_INFEAS
+  //          Iteration limit exceeded in Phase I
+  // 7          CPX_TIME_LIM_FEAS
+  //          Time limit exceeded in Phase II
+  // 8          CPX_TIME_LIM_INFEAS
+  //          Time limit exceeded in Phase I
+  // 9          CPX_NUM_BEST_FEAS
+  //          Problem non-optimal, singularities in Phase II
+  // 10         CPX_NUM_BEST_INFEAS
+  //          Problem non-optimal, singularities in Phase I
+  // 11         CPX_OPTIMAL_INFEAS
+  //          Optimal solution found, unscaled infeasibilities
+  // 12         CPX_ABORT_FEAS
+  //          Aborted in Phase II
+  // 13         CPX_ABORT_INFEAS
+  //          Aborted in Phase I
+  // 14          CPX_ABORT_DUAL_INFEAS
+  //          Aborted in barrier, dual infeasible
+  // 15          CPX_ABORT_PRIM_INFEAS
+  //          Aborted in barrier, primal infeasible
+  // 16          CPX_ABORT_PRIM_DUAL_INFEAS
+  //          Aborted in barrier, primal and dual infeasible
+  // 17          CPX_ABORT_PRIM_DUAL_FEAS
+  //          Aborted in barrier, primal and dual feasible
+  // 18          CPX_ABORT_CROSSOVER
+  //          Aborted in crossover
+  // 19          CPX_INForUNBD
+  //          Infeasible or unbounded
+  // 20   CPX_PIVOT
+  //       User pivot used
+  //
+  //     Ezeket hova tegyem:
+  // ??case CPX_ABORT_DUAL_INFEAS
+  // ??case CPX_ABORT_CROSSOVER
+  // ??case CPX_INForUNBD
+  // ??case CPX_PIVOT
+
+  //Some more interesting stuff:
+
+  // CPX_PARAM_PROBMETHOD  1062  int  LPMETHOD
+  // 0 Automatic
+  // 1 Primal Simplex
+  // 2 Dual Simplex
+  // 3 Network Simplex
+  // 4 Standard Barrier
+  // Default: 0
+  // Description: Method for linear optimization.
+  // Determines which algorithm is used when CPXlpopt() (or "optimize"
+  // in the Interactive Optimizer) is called. Currently the behavior of
+  // the "Automatic" setting is that CPLEX simply invokes the dual
+  // simplex method, but this capability may be expanded in the future
+  // so that CPLEX chooses the method based on problem characteristics
 #if CPX_VERSION < 900
-  void statusSwitch(CPXENVptr env,int& stat){
+  void statusSwitch(CPXENVptr cplexEnv(),int& stat){
     int lpmethod;
-    CPXgetintparam (env,CPX_PARAM_LPMETHOD,&lpmethod);
+    CPXgetintparam (cplexEnv(),CPX_PARAM_PROBMETHOD,&lpmethod);
     if (lpmethod==2){
       if (stat==CPX_UNBOUNDED){
@@ -536,7 +687,6 @@
 #endif
 
-  LpCplex::SolutionStatus LpCplex::_getPrimalStatus() const
-  {
-    //Unboundedness not treated well: the following is from cplex 9.0 doc
+  LpCplex::ProblemType LpCplex::_getPrimalType() const {
+    // Unboundedness not treated well: the following is from cplex 9.0 doc
     // About Unboundedness
 
@@ -553,20 +703,20 @@
     // has a feasible solution.
 
-    int stat = CPXgetstat(env, lp);
+    int stat = CPXgetstat(cplexEnv(), _prob);
 #if CPX_VERSION >= 800
     switch (stat)
-    {
+      {
       case CPX_STAT_OPTIMAL:
         return OPTIMAL;
       case CPX_STAT_UNBOUNDED:
-        return INFINITE;
+        return UNBOUNDED;
       case CPX_STAT_INFEASIBLE:
         return INFEASIBLE;
       default:
         return UNDEFINED;
-    }
+      }
 #else
-    statusSwitch(env,stat);
-    //CPXgetstat(env, lp);
+    statusSwitch(cplexEnv(),stat);
+    //CPXgetstat(cplexEnv(), _prob);
     //printf("A primal status: %d, CPX_OPTIMAL=%d \n",stat,CPX_OPTIMAL);
     switch (stat) {
@@ -577,22 +727,22 @@
     case CPX_UNBOUNDED://Unbounded
       return INFEASIBLE;//In case of dual simplex
-      //return INFINITE;
+      //return UNBOUNDED;
     case CPX_INFEASIBLE://Infeasible
- //    case CPX_IT_LIM_INFEAS:
-//     case CPX_TIME_LIM_INFEAS:
-//     case CPX_NUM_BEST_INFEAS:
-//     case CPX_OPTIMAL_INFEAS:
-//     case CPX_ABORT_INFEAS:
-//     case CPX_ABORT_PRIM_INFEAS:
-//     case CPX_ABORT_PRIM_DUAL_INFEAS:
-      return INFINITE;//In case of dual simplex
+      //    case CPX_IT_LIM_INFEAS:
+      //     case CPX_TIME_LIM_INFEAS:
+      //     case CPX_NUM_BEST_INFEAS:
+      //     case CPX_OPTIMAL_INFEAS:
+      //     case CPX_ABORT_INFEAS:
+      //     case CPX_ABORT_PRIM_INFEAS:
+      //     case CPX_ABORT_PRIM_DUAL_INFEAS:
+      return UNBOUNDED;//In case of dual simplex
       //return INFEASIBLE;
-//     case CPX_OBJ_LIM:
-//     case CPX_IT_LIM_FEAS:
-//     case CPX_TIME_LIM_FEAS:
-//     case CPX_NUM_BEST_FEAS:
-//     case CPX_ABORT_FEAS:
-//     case CPX_ABORT_PRIM_DUAL_FEAS:
-//       return FEASIBLE;
+      //     case CPX_OBJ_LIM:
+      //     case CPX_IT_LIM_FEAS:
+      //     case CPX_TIME_LIM_FEAS:
+      //     case CPX_NUM_BEST_FEAS:
+      //     case CPX_ABORT_FEAS:
+      //     case CPX_ABORT_PRIM_DUAL_FEAS:
+      //       return FEASIBLE;
     default:
       return UNDEFINED; //Everything else comes here
@@ -602,36 +752,34 @@
   }
 
-//9.0-as cplex verzio statusai
-// CPX_STAT_ABORT_DUAL_OBJ_LIM
-// CPX_STAT_ABORT_IT_LIM
-// CPX_STAT_ABORT_OBJ_LIM
-// CPX_STAT_ABORT_PRIM_OBJ_LIM
-// CPX_STAT_ABORT_TIME_LIM
-// CPX_STAT_ABORT_USER
-// CPX_STAT_FEASIBLE_RELAXED
-// CPX_STAT_INFEASIBLE
-// CPX_STAT_INForUNBD
-// CPX_STAT_NUM_BEST
-// CPX_STAT_OPTIMAL
-// CPX_STAT_OPTIMAL_FACE_UNBOUNDED
-// CPX_STAT_OPTIMAL_INFEAS
-// CPX_STAT_OPTIMAL_RELAXED
-// CPX_STAT_UNBOUNDED
-
-  LpCplex::SolutionStatus LpCplex::_getDualStatus() const
-  {
-    int stat = CPXgetstat(env, lp);
+  //9.0-as cplex verzio statusai
+  // CPX_STAT_ABORT_DUAL_OBJ_LIM
+  // CPX_STAT_ABORT_IT_LIM
+  // CPX_STAT_ABORT_OBJ_LIM
+  // CPX_STAT_ABORT_PRIM_OBJ_LIM
+  // CPX_STAT_ABORT_TIME_LIM
+  // CPX_STAT_ABORT_USER
+  // CPX_STAT_FEASIBLE_RELAXED
+  // CPX_STAT_INFEASIBLE
+  // CPX_STAT_INForUNBD
+  // CPX_STAT_NUM_BEST
+  // CPX_STAT_OPTIMAL
+  // CPX_STAT_OPTIMAL_FACE_UNBOUNDED
+  // CPX_STAT_OPTIMAL_INFEAS
+  // CPX_STAT_OPTIMAL_RELAXED
+  // CPX_STAT_UNBOUNDED
+
+  LpCplex::ProblemType LpCplex::_getDualType() const {
+    int stat = CPXgetstat(cplexEnv(), _prob);
 #if CPX_VERSION >= 800
-    switch (stat)
-    {
-      case CPX_STAT_OPTIMAL:
-        return OPTIMAL;
-      case CPX_STAT_UNBOUNDED:
-        return INFEASIBLE;
-      default:
-        return UNDEFINED;
+    switch (stat) {
+    case CPX_STAT_OPTIMAL:
+      return OPTIMAL;
+    case CPX_STAT_UNBOUNDED:
+      return INFEASIBLE;
+    default:
+      return UNDEFINED;
     }
 #else
-    statusSwitch(env,stat);
+    statusSwitch(cplexEnv(),stat);
     switch (stat) {
     case 0:
@@ -640,5 +788,5 @@
       return OPTIMAL;
     case CPX_UNBOUNDED:
-     return INFEASIBLE;
+      return INFEASIBLE;
     default:
       return UNDEFINED; //Everything else comes here
@@ -648,50 +796,128 @@
   }
 
-  LpCplex::ProblemTypes LpCplex::_getProblemType() const
-  {
-    int stat = CPXgetstat(env, lp);
-#if CPX_VERSION >= 800
-    switch (stat)
-    {
-      case CPX_STAT_OPTIMAL:
-        return PRIMAL_DUAL_FEASIBLE;
-      case CPX_STAT_UNBOUNDED:
-         return PRIMAL_FEASIBLE_DUAL_INFEASIBLE;
-      default:
-        return UNKNOWN;
-    }
+  // MipCplex members
+
+  MipCplex::MipCplex()
+    : LpBase(), CplexBase(), MipSolver() {
+
+#if CPX_VERSION < 800
+    CPXchgprobtype(cplexEnv(),  _prob, CPXPROB_MIP);
 #else
+    CPXchgprobtype(cplexEnv(),  _prob, CPXPROB_MILP);
+#endif
+  }
+
+  MipCplex::MipCplex(const CplexEnv& env)
+    : LpBase(), CplexBase(env), MipSolver() {
+
+#if CPX_VERSION < 800
+    CPXchgprobtype(cplexEnv(),  _prob, CPXPROB_MIP);
+#else
+    CPXchgprobtype(cplexEnv(),  _prob, CPXPROB_MILP);
+#endif
+
+  }
+
+  MipCplex::MipCplex(const MipCplex& other)
+    : LpBase(), CplexBase(other), MipSolver() {}
+
+  MipCplex::~MipCplex() {}
+
+  MipCplex* MipCplex::_newSolver() const { return new MipCplex; }
+  MipCplex* MipCplex::_cloneSolver() const {return new MipCplex(*this); }
+
+  const char* MipCplex::_solverName() const { return "MipCplex"; }
+
+  void MipCplex::_setColType(int i, MipCplex::ColTypes col_type) {
+
+    // Note If a variable is to be changed to binary, a call to CPXchgbds
+    // should also be made to change the bounds to 0 and 1.
+
+    switch (col_type){
+    case INTEGER: {
+      const char t = 'I';
+      CPXchgctype (cplexEnv(), _prob, 1, &i, &t);
+    } break;
+    case REAL: {
+      const char t = 'C';
+      CPXchgctype (cplexEnv(), _prob, 1, &i, &t);
+    } break;
+    default:
+      break;
+    }
+  }
+
+  MipCplex::ColTypes MipCplex::_getColType(int i) const {
+    char t;
+    CPXgetctype (cplexEnv(), _prob, &t, i, i);
+    switch (t) {
+    case 'I':
+      return INTEGER;
+    case 'C':
+      return REAL;
+    default:
+      LEMON_ASSERT(false, "Invalid column type");
+      return ColTypes();
+    }
+
+  }
+
+  MipCplex::SolveExitStatus MipCplex::_solve() {
+    int status;
+    status = CPXmipopt (cplexEnv(), _prob);
+    if (status==0)
+      return SOLVED;
+    else
+      return UNSOLVED;
+
+  }
+
+
+  MipCplex::ProblemType MipCplex::_getType() const {
+
+    int stat = CPXgetstat(cplexEnv(), _prob);
+
+    //Fortunately, MIP statuses did not change for cplex 8.0
     switch (stat) {
-    case CPX_OPTIMAL://Optimal
-        return PRIMAL_DUAL_FEASIBLE;
-    case CPX_UNBOUNDED:
-         return PRIMAL_FEASIBLE_DUAL_INFEASIBLE;
-//         return PRIMAL_INFEASIBLE_DUAL_FEASIBLE;
-//         return PRIMAL_DUAL_INFEASIBLE;
-
-//Seems to be that this is all we can say for sure
-    default:
-        //In all other cases
-        return UNKNOWN;
-      //FIXME error
-    }
-#endif
-  }
-
-  void LpCplex::_setMax()
-  {
-    CPXchgobjsen(env, lp, CPX_MAX);
-   }
-  void LpCplex::_setMin()
-  {
-    CPXchgobjsen(env, lp, CPX_MIN);
-   }
-
-  bool LpCplex::_isMax() const
-  {
-    if (CPXgetobjsen(env, lp)==CPX_MAX)
-      return true;
-    else
-      return false;
+    case CPXMIP_OPTIMAL:
+      // Optimal integer solution has been found.
+    case CPXMIP_OPTIMAL_TOL:
+      // Optimal soluton with the tolerance defined by epgap or epagap has
+      // been found.
+      return OPTIMAL;
+      //This also exists in later issues
+      //    case CPXMIP_UNBOUNDED:
+      //return UNBOUNDED;
+      case CPXMIP_INFEASIBLE:
+        return INFEASIBLE;
+    default:
+      return UNDEFINED;
+    }
+    //Unboundedness not treated well: the following is from cplex 9.0 doc
+    // About Unboundedness
+
+    // The treatment of models that are unbounded involves a few
+    // subtleties. Specifically, a declaration of unboundedness means that
+    // ILOG CPLEX has determined that the model has an unbounded
+    // ray. Given any feasible solution x with objective z, a multiple of
+    // the unbounded ray can be added to x to give a feasible solution
+    // with objective z-1 (or z+1 for maximization models). Thus, if a
+    // feasible solution exists, then the optimal objective is
+    // unbounded. Note that ILOG CPLEX has not necessarily concluded that
+    // a feasible solution exists. Users can call the routine CPXsolninfo
+    // to determine whether ILOG CPLEX has also concluded that the model
+    // has a feasible solution.
+  }
+
+  MipCplex::Value MipCplex::_getSol(int i) const {
+    Value x;
+    CPXgetmipx(cplexEnv(), _prob, &x, i, i);
+    return x;
+  }
+
+  MipCplex::Value MipCplex::_getSolValue() const {
+    Value objval;
+    CPXgetmipobjval(cplexEnv(), _prob, &objval);
+    return objval;
   }
 
Index: lemon/lp_cplex.h
===================================================================
--- lemon/lp_cplex.h	(revision 458)
+++ lemon/lp_cplex.h	(revision 459)
@@ -30,43 +30,89 @@
 namespace lemon {
 
-
-  /// \brief Interface for the CPLEX solver
-  ///
-  /// This class implements an interface for the CPLEX LP solver.
-  class LpCplex :virtual public LpSolverBase {
-
-  public:
-
-    typedef LpSolverBase Parent;
-
-    /// \e
-    int status;
-    cpxenv* env;
-    cpxlp* lp;
-
-
-    /// \e
-    LpCplex();
-    /// \e
-    LpCplex(const LpCplex&);
-    /// \e
-    ~LpCplex();
-
-  protected:
-    virtual LpSolverBase* _newLp();
-    virtual LpSolverBase* _copyLp();
-
+  /// \brief Reference counted wrapper around cpxenv pointer
+  ///
+  /// The cplex uses environment object which is responsible for
+  /// checking the proper license usage. This class provides a simple
+  /// interface for share the environment object between different
+  /// problems.
+  class CplexEnv {
+    friend class CplexBase;
+  private:
+    cpxenv* _env;
+    mutable int* _cnt;
+
+  public:
+
+    /// \brief This exception is thrown when the license check is not
+    /// sufficient
+    class LicenseError : public Exception {
+      friend class CplexEnv;
+    private:
+
+      LicenseError(int status);
+      char _message[510];
+
+    public:
+
+      /// The short error message
+      virtual const char* what() const throw() {
+        return _message;
+      }
+    };
+
+    /// Constructor
+    CplexEnv();
+    /// Shallow copy constructor
+    CplexEnv(const CplexEnv&);
+    /// Shallow assignement
+    CplexEnv& operator=(const CplexEnv&);
+    /// Destructor
+    virtual ~CplexEnv();
+
+  protected:
+
+    cpxenv* cplexEnv() { return _env; }
+    const cpxenv* cplexEnv() const { return _env; }
+  };
+
+  /// \brief Base interface for the CPLEX LP and MIP solver
+  ///
+  /// This class implements the common interface of the CPLEX LP and
+  /// MIP solvers.  
+  /// \ingroup lp_group
+  class CplexBase : virtual public LpBase {
+  protected:
+
+    CplexEnv _env;
+    cpxlp* _prob;
+
+    CplexBase();
+    CplexBase(const CplexEnv&);
+    CplexBase(const CplexBase &);
+    virtual ~CplexBase();
 
     virtual int _addCol();
     virtual int _addRow();
+
     virtual void _eraseCol(int i);
     virtual void _eraseRow(int i);
-    virtual void _getColName(int col, std::string & name) const;
-    virtual void _setColName(int col, const std::string & name);
+
+    virtual void _eraseColId(int i);
+    virtual void _eraseRowId(int i);
+
+    virtual void _getColName(int col, std::string& name) const;
+    virtual void _setColName(int col, const std::string& name);
     virtual int _colByName(const std::string& name) const;
-    virtual void _setRowCoeffs(int i, ConstRowIterator b, ConstRowIterator e);
-    virtual void _getRowCoeffs(int i, RowIterator b) const;
-    virtual void _setColCoeffs(int i, ConstColIterator b, ConstColIterator e);
-    virtual void _getColCoeffs(int i, ColIterator b) const;
+
+    virtual void _getRowName(int row, std::string& name) const;
+    virtual void _setRowName(int row, const std::string& name);
+    virtual int _rowByName(const std::string& name) const;
+
+    virtual void _setRowCoeffs(int i, ExprIterator b, ExprIterator e);
+    virtual void _getRowCoeffs(int i, InsertIterator b) const;
+
+    virtual void _setColCoeffs(int i, ExprIterator b, ExprIterator e);
+    virtual void _getColCoeffs(int i, InsertIterator b) const;
+
     virtual void _setCoeff(int row, int col, Value value);
     virtual Value _getCoeff(int row, int col) const;
@@ -74,15 +120,75 @@
     virtual void _setColLowerBound(int i, Value value);
     virtual Value _getColLowerBound(int i) const;
+
     virtual void _setColUpperBound(int i, Value value);
     virtual Value _getColUpperBound(int i) const;
 
-//     virtual void _setRowLowerBound(int i, Value value);
-//     virtual void _setRowUpperBound(int i, Value value);
-    virtual void _setRowBounds(int i, Value lower, Value upper);
-    virtual void _getRowBounds(int i, Value &lb, Value &ub) const;
+  private:
+    void _set_row_bounds(int i, Value lb, Value ub);
+  protected:
+
+    virtual void _setRowLowerBound(int i, Value value);
+    virtual Value _getRowLowerBound(int i) const;
+
+    virtual void _setRowUpperBound(int i, Value value);
+    virtual Value _getRowUpperBound(int i) const;
+
+    virtual void _setObjCoeffs(ExprIterator b, ExprIterator e);
+    virtual void _getObjCoeffs(InsertIterator b) const;
+
     virtual void _setObjCoeff(int i, Value obj_coef);
     virtual Value _getObjCoeff(int i) const;
-    virtual void _clearObj();
-
+
+    virtual void _setSense(Sense sense);
+    virtual Sense _getSense() const;
+
+    virtual void _clear();
+
+  public:
+
+    /// Returns the used \c CplexEnv instance
+    const CplexEnv& env() const { return _env; }
+    ///
+    const cpxenv* cplexEnv() const { return _env.cplexEnv(); }
+
+    cpxlp* cplexLp() { return _prob; }
+    const cpxlp* cplexLp() const { return _prob; }
+
+  };
+
+  /// \brief Interface for the CPLEX LP solver
+  ///
+  /// This class implements an interface for the CPLEX LP solver.
+  ///\ingroup lp_group
+  class LpCplex : public CplexBase, public LpSolver {
+  public:
+    /// \e
+    LpCplex();
+    /// \e
+    LpCplex(const CplexEnv&);
+    /// \e
+    LpCplex(const LpCplex&);
+    /// \e
+    virtual ~LpCplex();
+
+  private:
+
+    // these values cannot retrieved element by element
+    mutable std::vector<int> _col_status;
+    mutable std::vector<int> _row_status;
+
+    mutable std::vector<Value> _primal_ray;
+    mutable std::vector<Value> _dual_ray;
+
+    void _clear_temporals();
+
+    SolveExitStatus convertStatus(int status);
+
+  protected:
+
+    virtual LpCplex* _cloneSolver() const;
+    virtual LpCplex* _newSolver() const;
+
+    virtual const char* _solverName() const;
 
     virtual SolveExitStatus _solve();
@@ -90,22 +196,59 @@
     virtual Value _getDual(int i) const;
     virtual Value _getPrimalValue() const;
-    virtual bool _isBasicCol(int i) const;
-
-    virtual SolutionStatus _getPrimalStatus() const;
-    virtual SolutionStatus _getDualStatus() const;
-    virtual ProblemTypes _getProblemType() const;
-
-
-    virtual void _setMax();
-    virtual void _setMin();
-
-    virtual bool _isMax() const;
-
-  public:
-
-    cpxenv* cplexEnv() { return env; }
-    cpxlp* cplexLp() { return lp; }
-
-  };
+
+    virtual VarStatus _getColStatus(int i) const;
+    virtual VarStatus _getRowStatus(int i) const;
+
+    virtual Value _getPrimalRay(int i) const;
+    virtual Value _getDualRay(int i) const;
+
+    virtual ProblemType _getPrimalType() const;
+    virtual ProblemType _getDualType() const;
+
+  public:
+
+    /// Solve with primal simplex method
+    SolveExitStatus solvePrimal();
+
+    /// Solve with dual simplex method
+    SolveExitStatus solveDual();
+
+    /// Solve with barrier method
+    SolveExitStatus solveBarrier();
+
+  };
+
+  /// \brief Interface for the CPLEX MIP solver
+  ///
+  /// This class implements an interface for the CPLEX MIP solver.
+  ///\ingroup lp_group
+  class MipCplex : public CplexBase, public MipSolver {
+  public:
+    /// \e
+    MipCplex();
+    /// \e
+    MipCplex(const CplexEnv&);
+    /// \e
+    MipCplex(const MipCplex&);
+    /// \e
+    virtual ~MipCplex();
+
+  protected:
+
+    virtual MipCplex* _cloneSolver() const;
+    virtual MipCplex* _newSolver() const;
+
+    virtual const char* _solverName() const;
+
+    virtual ColTypes _getColType(int col) const;
+    virtual void _setColType(int col, ColTypes col_type);
+
+    virtual SolveExitStatus _solve();
+    virtual ProblemType _getType() const;
+    virtual Value _getSol(int i) const;
+    virtual Value _getSolValue() const;
+
+  };
+
 } //END OF NAMESPACE LEMON
 
Index: lemon/lp_glpk.cc
===================================================================
--- lemon/lp_glpk.cc	(revision 458)
+++ lemon/lp_glpk.cc	(revision 459)
@@ -18,627 +18,935 @@
 
 ///\file
-///\brief Implementation of the LEMON-GLPK lp solver interface.
+///\brief Implementation of the LEMON GLPK LP and MIP solver interface.
 
 #include <lemon/lp_glpk.h>
-//#include <iostream>
-
-extern "C" {
 #include <glpk.h>
-}
-
-#if GLP_MAJOR_VERSION > 4 || (GLP_MAJOR_VERSION == 4 && GLP_MINOR_VERSION > 15)
-#define LEMON_glp(func) (glp_##func)
-#define LEMON_lpx(func) (lpx_##func)
-
-#define LEMON_GLP(def) (GLP_##def)
-#define LEMON_LPX(def) (LPX_##def)
-
-#else
-
-#define LEMON_glp(func) (lpx_##func)
-#define LEMON_lpx(func) (lpx_##func)
-
-#define LEMON_GLP(def) (LPX_##def)
-#define LEMON_LPX(def) (LPX_##def)
-
-#endif
+
+#include <lemon/assert.h>
 
 namespace lemon {
 
-  LpGlpk::LpGlpk() : Parent() {
-    solved = false;
-    rows = _lp_bits::LpId(1);
-    cols = _lp_bits::LpId(1);
-    lp = LEMON_glp(create_prob)();
-    LEMON_glp(create_index)(lp);
-    messageLevel(0);
-  }
-
-  LpGlpk::LpGlpk(const LpGlpk &glp) : Parent() {
-    solved = false;
-    rows = _lp_bits::LpId(1);
-    cols = _lp_bits::LpId(1);
-    lp = LEMON_glp(create_prob)();
-    LEMON_glp(create_index)(lp);
-    messageLevel(0);
-    //Coefficient matrix, row bounds
-    LEMON_glp(add_rows)(lp, LEMON_glp(get_num_rows)(glp.lp));
-    LEMON_glp(add_cols)(lp, LEMON_glp(get_num_cols)(glp.lp));
-    int len;
-    std::vector<int> ind(1+LEMON_glp(get_num_cols)(glp.lp));
-    std::vector<Value> val(1+LEMON_glp(get_num_cols)(glp.lp));
-    for (int i=1;i<=LEMON_glp(get_num_rows)(glp.lp);++i)
-      {
-        len=LEMON_glp(get_mat_row)(glp.lp,i,&*ind.begin(),&*val.begin());
-        LEMON_glp(set_mat_row)(lp, i,len,&*ind.begin(),&*val.begin());
-        LEMON_glp(set_row_bnds)(lp,i,
-                                LEMON_glp(get_row_type)(glp.lp,i),
-                                LEMON_glp(get_row_lb)(glp.lp,i),
-                                LEMON_glp(get_row_ub)(glp.lp,i));
-      }
-
-    //Objective function, coloumn bounds
-    LEMON_glp(set_obj_dir)(lp, LEMON_glp(get_obj_dir)(glp.lp));
-    //Objectif function's constant term treated separately
-    LEMON_glp(set_obj_coef)(lp,0,LEMON_glp(get_obj_coef)(glp.lp,0));
-    for (int i=1;i<=LEMON_glp(get_num_cols)(glp.lp);++i)
-      {
-        LEMON_glp(set_obj_coef)(lp,i,
-                                LEMON_glp(get_obj_coef)(glp.lp,i));
-        LEMON_glp(set_col_bnds)(lp,i,
-                                LEMON_glp(get_col_type)(glp.lp,i),
-                                LEMON_glp(get_col_lb)(glp.lp,i),
-                                LEMON_glp(get_col_ub)(glp.lp,i));
-      }
-    rows = glp.rows;
-    cols = glp.cols;
-  }
-
-  LpGlpk::~LpGlpk() {
-    LEMON_glp(delete_prob)(lp);
-  }
-
-  int LpGlpk::_addCol() {
-    int i=LEMON_glp(add_cols)(lp, 1);
-    LEMON_glp(set_col_bnds)(lp, i, LEMON_GLP(FR), 0.0, 0.0);
-    solved = false;
+  // GlpkBase members
+
+  GlpkBase::GlpkBase() : LpBase() {
+    lp = glp_create_prob();
+    glp_create_index(lp);
+  }
+
+  GlpkBase::GlpkBase(const GlpkBase &other) : LpBase() {
+    lp = glp_create_prob();
+    glp_copy_prob(lp, other.lp, GLP_ON);
+    glp_create_index(lp);
+    rows = other.rows;
+    cols = other.cols;
+  }
+
+  GlpkBase::~GlpkBase() {
+    glp_delete_prob(lp);
+  }
+
+  int GlpkBase::_addCol() {
+    int i = glp_add_cols(lp, 1);
+    glp_set_col_bnds(lp, i, GLP_FR, 0.0, 0.0);
     return i;
   }
 
-  ///\e
-
-
-  LpSolverBase* LpGlpk::_newLp()
-  {
-    LpGlpk* newlp = new LpGlpk;
-    return newlp;
-  }
-
-  ///\e
-
-  LpSolverBase* LpGlpk::_copyLp()
-  {
-    LpGlpk *newlp = new LpGlpk(*this);
-    return newlp;
-  }
-
-  int LpGlpk::_addRow() {
-    int i=LEMON_glp(add_rows)(lp, 1);
-    solved = false;
+  int GlpkBase::_addRow() {
+    int i = glp_add_rows(lp, 1);
+    glp_set_row_bnds(lp, i, GLP_FR, 0.0, 0.0);
     return i;
   }
 
-
-  void LpGlpk::_eraseCol(int i) {
+  void GlpkBase::_eraseCol(int i) {
     int ca[2];
-    ca[1]=i;
-    LEMON_glp(del_cols)(lp, 1, ca);
-    solved = false;
-  }
-
-  void LpGlpk::_eraseRow(int i) {
+    ca[1] = i;
+    glp_del_cols(lp, 1, ca);
+  }
+
+  void GlpkBase::_eraseRow(int i) {
     int ra[2];
-    ra[1]=i;
-    LEMON_glp(del_rows)(lp, 1, ra);
-    solved = false;
-  }
-
-  void LpGlpk::_getColName(int c, std::string & name) const
-  {
-
-    const char *n = LEMON_glp(get_col_name)(lp,c);
-    name = n?n:"";
-  }
-
-
-  void LpGlpk::_setColName(int c, const std::string & name)
-  {
-    LEMON_glp(set_col_name)(lp,c,const_cast<char*>(name.c_str()));
-
-  }
-
-  int LpGlpk::_colByName(const std::string& name) const
-  {
-    int k = LEMON_glp(find_col)(lp, const_cast<char*>(name.c_str()));
+    ra[1] = i;
+    glp_del_rows(lp, 1, ra);
+  }
+
+  void GlpkBase::_eraseColId(int i) {
+    cols.eraseIndex(i);
+    cols.shiftIndices(i);
+  }
+
+  void GlpkBase::_eraseRowId(int i) {
+    rows.eraseIndex(i);
+    rows.shiftIndices(i);
+  }
+
+  void GlpkBase::_getColName(int c, std::string& name) const {
+    const char *str = glp_get_col_name(lp, c);
+    if (str) name = str;
+    else name.clear();
+  }
+
+  void GlpkBase::_setColName(int c, const std::string & name) {
+    glp_set_col_name(lp, c, const_cast<char*>(name.c_str()));
+
+  }
+
+  int GlpkBase::_colByName(const std::string& name) const {
+    int k = glp_find_col(lp, const_cast<char*>(name.c_str()));
     return k > 0 ? k : -1;
   }
 
-
-  void LpGlpk::_setRowCoeffs(int i, ConstRowIterator b, ConstRowIterator e)
-  {
-    std::vector<int> indices;
+  void GlpkBase::_getRowName(int r, std::string& name) const {
+    const char *str = glp_get_row_name(lp, r);
+    if (str) name = str;
+    else name.clear();
+  }
+
+  void GlpkBase::_setRowName(int r, const std::string & name) {
+    glp_set_row_name(lp, r, const_cast<char*>(name.c_str()));
+
+  }
+
+  int GlpkBase::_rowByName(const std::string& name) const {
+    int k = glp_find_row(lp, const_cast<char*>(name.c_str()));
+    return k > 0 ? k : -1;
+  }
+
+  void GlpkBase::_setRowCoeffs(int i, ExprIterator b, ExprIterator e) {
+    std::vector<int> indexes;
     std::vector<Value> values;
 
-    indices.push_back(0);
+    indexes.push_back(0);
     values.push_back(0);
 
-    for(ConstRowIterator it=b; it!=e; ++it) {
-      indices.push_back(it->first);
+    for(ExprIterator it = b; it != e; ++it) {
+      indexes.push_back(it->first);
       values.push_back(it->second);
     }
 
-    LEMON_glp(set_mat_row)(lp, i, values.size() - 1,
-                                &indices[0], &values[0]);
-
-    solved = false;
-  }
-
-  void LpGlpk::_getRowCoeffs(int ix, RowIterator b) const
-  {
-    int length = LEMON_glp(get_mat_row)(lp, ix, 0, 0);
-
-    std::vector<int> indices(length + 1);
+    glp_set_mat_row(lp, i, values.size() - 1,
+                    &indexes.front(), &values.front());
+  }
+
+  void GlpkBase::_getRowCoeffs(int ix, InsertIterator b) const {
+    int length = glp_get_mat_row(lp, ix, 0, 0);
+
+    std::vector<int> indexes(length + 1);
     std::vector<Value> values(length + 1);
 
-    LEMON_glp(get_mat_row)(lp, ix, &indices[0], &values[0]);
+    glp_get_mat_row(lp, ix, &indexes.front(), &values.front());
 
     for (int i = 1; i <= length; ++i) {
-      *b = std::make_pair(indices[i], values[i]);
+      *b = std::make_pair(indexes[i], values[i]);
       ++b;
     }
   }
 
-  void LpGlpk::_setColCoeffs(int ix, ConstColIterator b, ConstColIterator e) {
-
-    std::vector<int> indices;
+  void GlpkBase::_setColCoeffs(int ix, ExprIterator b,
+                                     ExprIterator e) {
+
+    std::vector<int> indexes;
     std::vector<Value> values;
 
-    indices.push_back(0);
+    indexes.push_back(0);
     values.push_back(0);
 
-    for(ConstColIterator it=b; it!=e; ++it) {
-      indices.push_back(it->first);
+    for(ExprIterator it = b; it != e; ++it) {
+      indexes.push_back(it->first);
       values.push_back(it->second);
     }
 
-    LEMON_glp(set_mat_col)(lp, ix, values.size() - 1,
-                                &indices[0], &values[0]);
-
-    solved = false;
-  }
-
-  void LpGlpk::_getColCoeffs(int ix, ColIterator b) const
-  {
-    int length = LEMON_glp(get_mat_col)(lp, ix, 0, 0);
-
-    std::vector<int> indices(length + 1);
+    glp_set_mat_col(lp, ix, values.size() - 1,
+                    &indexes.front(), &values.front());
+  }
+
+  void GlpkBase::_getColCoeffs(int ix, InsertIterator b) const {
+    int length = glp_get_mat_col(lp, ix, 0, 0);
+
+    std::vector<int> indexes(length + 1);
     std::vector<Value> values(length + 1);
 
-    LEMON_glp(get_mat_col)(lp, ix, &indices[0], &values[0]);
-
-    for (int i = 1; i <= length; ++i) {
-      *b = std::make_pair(indices[i], values[i]);
+    glp_get_mat_col(lp, ix, &indexes.front(), &values.front());
+
+    for (int i = 1; i  <= length; ++i) {
+      *b = std::make_pair(indexes[i], values[i]);
       ++b;
     }
   }
 
-  void LpGlpk::_setCoeff(int ix, int jx, Value value)
-  {
-
-    if (LEMON_glp(get_num_cols)(lp) < LEMON_glp(get_num_rows)(lp)) {
-
-      int length=LEMON_glp(get_mat_row)(lp, ix, 0, 0);
-
-      std::vector<int> indices(length + 2);
+  void GlpkBase::_setCoeff(int ix, int jx, Value value) {
+
+    if (glp_get_num_cols(lp) < glp_get_num_rows(lp)) {
+
+      int length = glp_get_mat_row(lp, ix, 0, 0);
+
+      std::vector<int> indexes(length + 2);
       std::vector<Value> values(length + 2);
 
-      LEMON_glp(get_mat_row)(lp, ix, &indices[0], &values[0]);
+      glp_get_mat_row(lp, ix, &indexes.front(), &values.front());
 
       //The following code does not suppose that the elements of the
-      //array indices are sorted
-      bool found=false;
-      for (int i = 1; i <= length; ++i) {
-        if (indices[i]==jx){
-          found=true;
-          values[i]=value;
+      //array indexes are sorted
+      bool found = false;
+      for (int i = 1; i  <= length; ++i) {
+        if (indexes[i] == jx) {
+          found = true;
+          values[i] = value;
           break;
         }
       }
-      if (!found){
+      if (!found) {
         ++length;
-        indices[length]=jx;
-        values[length]=value;
-      }
-
-      LEMON_glp(set_mat_row)(lp, ix, length, &indices[0], &values[0]);
+        indexes[length] = jx;
+        values[length] = value;
+      }
+
+      glp_set_mat_row(lp, ix, length, &indexes.front(), &values.front());
 
     } else {
 
-      int length=LEMON_glp(get_mat_col)(lp, jx, 0, 0);
-
-      std::vector<int> indices(length + 2);
+      int length = glp_get_mat_col(lp, jx, 0, 0);
+
+      std::vector<int> indexes(length + 2);
       std::vector<Value> values(length + 2);
 
-      LEMON_glp(get_mat_col)(lp, jx, &indices[0], &values[0]);
+      glp_get_mat_col(lp, jx, &indexes.front(), &values.front());
 
       //The following code does not suppose that the elements of the
-      //array indices are sorted
-      bool found=false;
+      //array indexes are sorted
+      bool found = false;
       for (int i = 1; i <= length; ++i) {
-        if (indices[i]==ix){
-          found=true;
-          values[i]=value;
+        if (indexes[i] == ix) {
+          found = true;
+          values[i] = value;
           break;
         }
       }
-      if (!found){
+      if (!found) {
         ++length;
-        indices[length]=ix;
-        values[length]=value;
-      }
-
-      LEMON_glp(set_mat_col)(lp, jx, length, &indices[0], &values[0]);
-    }
-
-    solved = false;
-  }
-
-  LpGlpk::Value LpGlpk::_getCoeff(int ix, int jx) const
-  {
-
-    int length=LEMON_glp(get_mat_row)(lp, ix, 0, 0);
-
-    std::vector<int> indices(length + 1);
+        indexes[length] = ix;
+        values[length] = value;
+      }
+
+      glp_set_mat_col(lp, jx, length, &indexes.front(), &values.front());
+    }
+
+  }
+
+  GlpkBase::Value GlpkBase::_getCoeff(int ix, int jx) const {
+
+    int length = glp_get_mat_row(lp, ix, 0, 0);
+
+    std::vector<int> indexes(length + 1);
     std::vector<Value> values(length + 1);
 
-    LEMON_glp(get_mat_row)(lp, ix, &indices[0], &values[0]);
-
-    //The following code does not suppose that the elements of the
-    //array indices are sorted
-    for (int i = 1; i <= length; ++i) {
-      if (indices[i]==jx){
+    glp_get_mat_row(lp, ix, &indexes.front(), &values.front());
+
+    for (int i = 1; i  <= length; ++i) {
+      if (indexes[i] == jx) {
         return values[i];
       }
     }
+
     return 0;
-
-  }
-
-
-  void LpGlpk::_setColLowerBound(int i, Value lo)
-  {
-    if (lo==INF) {
-      //FIXME error
-    }
-    int b=LEMON_glp(get_col_type)(lp, i);
-    double up=LEMON_glp(get_col_ub)(lp, i);
-    if (lo==-INF) {
+  }
+
+  void GlpkBase::_setColLowerBound(int i, Value lo) {
+    LEMON_ASSERT(lo != INF, "Invalid bound");
+
+    int b = glp_get_col_type(lp, i);
+    double up = glp_get_col_ub(lp, i);
+    if (lo == -INF) {
       switch (b) {
-      case LEMON_GLP(FR):
-      case LEMON_GLP(LO):
-        LEMON_glp(set_col_bnds)(lp, i, LEMON_GLP(FR), lo, up);
-        break;
-      case LEMON_GLP(UP):
-        break;
-      case LEMON_GLP(DB):
-      case LEMON_GLP(FX):
-        LEMON_glp(set_col_bnds)(lp, i, LEMON_GLP(UP), lo, up);
-        break;
-      default: ;
-        //FIXME error
+      case GLP_FR:
+      case GLP_LO:
+        glp_set_col_bnds(lp, i, GLP_FR, lo, up);
+        break;
+      case GLP_UP:
+        break;
+      case GLP_DB:
+      case GLP_FX:
+        glp_set_col_bnds(lp, i, GLP_UP, lo, up);
+        break;
+      default:
+        break;
       }
     } else {
       switch (b) {
-      case LEMON_GLP(FR):
-      case LEMON_GLP(LO):
-        LEMON_glp(set_col_bnds)(lp, i, LEMON_GLP(LO), lo, up);
-        break;
-      case LEMON_GLP(UP):
-      case LEMON_GLP(DB):
-      case LEMON_GLP(FX):
-        if (lo==up)
-          LEMON_glp(set_col_bnds)(lp, i, LEMON_GLP(FX), lo, up);
+      case GLP_FR:
+      case GLP_LO:
+        glp_set_col_bnds(lp, i, GLP_LO, lo, up);
+        break;
+      case GLP_UP:
+      case GLP_DB:
+      case GLP_FX:
+        if (lo == up)
+          glp_set_col_bnds(lp, i, GLP_FX, lo, up);
         else
-          LEMON_glp(set_col_bnds)(lp, i, LEMON_GLP(DB), lo, up);
-        break;
-      default: ;
-        //FIXME error
-      }
-    }
-
-    solved = false;
-  }
-
-  LpGlpk::Value LpGlpk::_getColLowerBound(int i) const
-  {
-    int b=LEMON_glp(get_col_type)(lp, i);
+          glp_set_col_bnds(lp, i, GLP_DB, lo, up);
+        break;
+      default:
+        break;
+      }
+    }
+  }
+
+  GlpkBase::Value GlpkBase::_getColLowerBound(int i) const {
+    int b = glp_get_col_type(lp, i);
+    switch (b) {
+    case GLP_LO:
+    case GLP_DB:
+    case GLP_FX:
+      return glp_get_col_lb(lp, i);
+    default:
+      return -INF;
+    }
+  }
+
+  void GlpkBase::_setColUpperBound(int i, Value up) {
+    LEMON_ASSERT(up != -INF, "Invalid bound");
+
+    int b = glp_get_col_type(lp, i);
+    double lo = glp_get_col_lb(lp, i);
+    if (up == INF) {
       switch (b) {
-      case LEMON_GLP(LO):
-      case LEMON_GLP(DB):
-      case LEMON_GLP(FX):
-        return LEMON_glp(get_col_lb)(lp, i);
-      default: ;
-        return -INF;
-      }
-  }
-
-  void LpGlpk::_setColUpperBound(int i, Value up)
-  {
-    if (up==-INF) {
-      //FIXME error
-    }
-    int b=LEMON_glp(get_col_type)(lp, i);
-    double lo=LEMON_glp(get_col_lb)(lp, i);
-    if (up==INF) {
-      switch (b) {
-      case LEMON_GLP(FR):
-      case LEMON_GLP(LO):
-        break;
-      case LEMON_GLP(UP):
-        LEMON_glp(set_col_bnds)(lp, i, LEMON_GLP(FR), lo, up);
-        break;
-      case LEMON_GLP(DB):
-      case LEMON_GLP(FX):
-        LEMON_glp(set_col_bnds)(lp, i, LEMON_GLP(LO), lo, up);
-        break;
-      default: ;
-        //FIXME error
+      case GLP_FR:
+      case GLP_LO:
+        break;
+      case GLP_UP:
+        glp_set_col_bnds(lp, i, GLP_FR, lo, up);
+        break;
+      case GLP_DB:
+      case GLP_FX:
+        glp_set_col_bnds(lp, i, GLP_LO, lo, up);
+        break;
+      default:
+        break;
       }
     } else {
       switch (b) {
-      case LEMON_GLP(FR):
-        LEMON_glp(set_col_bnds)(lp, i, LEMON_GLP(UP), lo, up);
-        break;
-      case LEMON_GLP(UP):
-        LEMON_glp(set_col_bnds)(lp, i, LEMON_GLP(UP), lo, up);
-        break;
-      case LEMON_GLP(LO):
-      case LEMON_GLP(DB):
-      case LEMON_GLP(FX):
-        if (lo==up)
-          LEMON_glp(set_col_bnds)(lp, i, LEMON_GLP(FX), lo, up);
+      case GLP_FR:
+        glp_set_col_bnds(lp, i, GLP_UP, lo, up);
+        break;
+      case GLP_UP:
+        glp_set_col_bnds(lp, i, GLP_UP, lo, up);
+        break;
+      case GLP_LO:
+      case GLP_DB:
+      case GLP_FX:
+        if (lo == up)
+          glp_set_col_bnds(lp, i, GLP_FX, lo, up);
         else
-          LEMON_glp(set_col_bnds)(lp, i, LEMON_GLP(DB), lo, up);
-        break;
-      default: ;
-        //FIXME error
-      }
-    }
-
-    solved = false;
-  }
-
-  LpGlpk::Value LpGlpk::_getColUpperBound(int i) const
-  {
-    int b=LEMON_glp(get_col_type)(lp, i);
+          glp_set_col_bnds(lp, i, GLP_DB, lo, up);
+        break;
+      default:
+        break;
+      }
+    }
+
+  }
+
+  GlpkBase::Value GlpkBase::_getColUpperBound(int i) const {
+    int b = glp_get_col_type(lp, i);
       switch (b) {
-      case LEMON_GLP(UP):
-      case LEMON_GLP(DB):
-      case LEMON_GLP(FX):
-        return LEMON_glp(get_col_ub)(lp, i);
-      default: ;
+      case GLP_UP:
+      case GLP_DB:
+      case GLP_FX:
+        return glp_get_col_ub(lp, i);
+      default:
         return INF;
       }
   }
 
-  void LpGlpk::_setRowBounds(int i, Value lb, Value ub)
-  {
-    //Bad parameter
-    if (lb==INF || ub==-INF) {
-      //FIXME error
-    }
-
-    if (lb == -INF){
-      if (ub == INF){
-        LEMON_glp(set_row_bnds)(lp, i, LEMON_GLP(FR), lb, ub);
-      }
-      else{
-        LEMON_glp(set_row_bnds)(lp, i, LEMON_GLP(UP), lb, ub);
-      }
-    }
-    else{
-      if (ub==INF){
-        LEMON_glp(set_row_bnds)(lp, i, LEMON_GLP(LO), lb, ub);
-
-      }
-      else{
-        if (lb == ub){
-          LEMON_glp(set_row_bnds)(lp, i, LEMON_GLP(FX), lb, ub);
+  void GlpkBase::_setRowLowerBound(int i, Value lo) {
+    LEMON_ASSERT(lo != INF, "Invalid bound");
+
+    int b = glp_get_row_type(lp, i);
+    double up = glp_get_row_ub(lp, i);
+    if (lo == -INF) {
+      switch (b) {
+      case GLP_FR:
+      case GLP_LO:
+        glp_set_row_bnds(lp, i, GLP_FR, lo, up);
+        break;
+      case GLP_UP:
+        break;
+      case GLP_DB:
+      case GLP_FX:
+        glp_set_row_bnds(lp, i, GLP_UP, lo, up);
+        break;
+      default:
+        break;
+      }
+    } else {
+      switch (b) {
+      case GLP_FR:
+      case GLP_LO:
+        glp_set_row_bnds(lp, i, GLP_LO, lo, up);
+        break;
+      case GLP_UP:
+      case GLP_DB:
+      case GLP_FX:
+        if (lo == up)
+          glp_set_row_bnds(lp, i, GLP_FX, lo, up);
+        else
+          glp_set_row_bnds(lp, i, GLP_DB, lo, up);
+        break;
+      default:
+        break;
+      }
+    }
+
+  }
+
+  GlpkBase::Value GlpkBase::_getRowLowerBound(int i) const {
+    int b = glp_get_row_type(lp, i);
+    switch (b) {
+    case GLP_LO:
+    case GLP_DB:
+    case GLP_FX:
+      return glp_get_row_lb(lp, i);
+    default:
+      return -INF;
+    }
+  }
+
+  void GlpkBase::_setRowUpperBound(int i, Value up) {
+    LEMON_ASSERT(up != -INF, "Invalid bound");
+
+    int b = glp_get_row_type(lp, i);
+    double lo = glp_get_row_lb(lp, i);
+    if (up == INF) {
+      switch (b) {
+      case GLP_FR:
+      case GLP_LO:
+        break;
+      case GLP_UP:
+        glp_set_row_bnds(lp, i, GLP_FR, lo, up);
+        break;
+      case GLP_DB:
+      case GLP_FX:
+        glp_set_row_bnds(lp, i, GLP_LO, lo, up);
+        break;
+      default:
+        break;
+      }
+    } else {
+      switch (b) {
+      case GLP_FR:
+        glp_set_row_bnds(lp, i, GLP_UP, lo, up);
+        break;
+      case GLP_UP:
+        glp_set_row_bnds(lp, i, GLP_UP, lo, up);
+        break;
+      case GLP_LO:
+      case GLP_DB:
+      case GLP_FX:
+        if (lo == up)
+          glp_set_row_bnds(lp, i, GLP_FX, lo, up);
+        else
+          glp_set_row_bnds(lp, i, GLP_DB, lo, up);
+        break;
+      default:
+        break;
+      }
+    }
+  }
+
+  GlpkBase::Value GlpkBase::_getRowUpperBound(int i) const {
+    int b = glp_get_row_type(lp, i);
+    switch (b) {
+    case GLP_UP:
+    case GLP_DB:
+    case GLP_FX:
+      return glp_get_row_ub(lp, i);
+    default:
+      return INF;
+    }
+  }
+
+  void GlpkBase::_setObjCoeffs(ExprIterator b, ExprIterator e) {
+    for (int i = 1; i <= glp_get_num_cols(lp); ++i) {
+      glp_set_obj_coef(lp, i, 0.0);
+    }
+    for (ExprIterator it = b; it != e; ++it) {
+      glp_set_obj_coef(lp, it->first, it->second);
+    }
+  }
+
+  void GlpkBase::_getObjCoeffs(InsertIterator b) const {
+    for (int i = 1; i <= glp_get_num_cols(lp); ++i) {
+      Value val = glp_get_obj_coef(lp, i);
+      if (val != 0.0) {
+        *b = std::make_pair(i, val);
+        ++b;
+      }
+    }
+  }
+
+  void GlpkBase::_setObjCoeff(int i, Value obj_coef) {
+    //i = 0 means the constant term (shift)
+    glp_set_obj_coef(lp, i, obj_coef);
+  }
+
+  GlpkBase::Value GlpkBase::_getObjCoeff(int i) const {
+    //i = 0 means the constant term (shift)
+    return glp_get_obj_coef(lp, i);
+  }
+
+  void GlpkBase::_setSense(GlpkBase::Sense sense) {
+    switch (sense) {
+    case MIN:
+      glp_set_obj_dir(lp, GLP_MIN);
+      break;
+    case MAX:
+      glp_set_obj_dir(lp, GLP_MAX);
+      break;
+    }
+  }
+
+  GlpkBase::Sense GlpkBase::_getSense() const {
+    switch(glp_get_obj_dir(lp)) {
+    case GLP_MIN:
+      return MIN;
+    case GLP_MAX:
+      return MAX;
+    default:
+      LEMON_ASSERT(false, "Wrong sense");
+      return GlpkBase::Sense();
+    }
+  }
+
+  void GlpkBase::_clear() {
+    glp_erase_prob(lp);
+    rows.clear();
+    cols.clear();
+  }
+
+  // LpGlpk members
+
+  LpGlpk::LpGlpk()
+    : LpBase(), GlpkBase(), LpSolver() {
+    messageLevel(MESSAGE_NO_OUTPUT);
+  }
+
+  LpGlpk::LpGlpk(const LpGlpk& other)
+    : LpBase(other), GlpkBase(other), LpSolver(other) {
+    messageLevel(MESSAGE_NO_OUTPUT);
+  }
+
+  LpGlpk* LpGlpk::_newSolver() const { return new LpGlpk; }
+  LpGlpk* LpGlpk::_cloneSolver() const { return new LpGlpk(*this); }
+
+  const char* LpGlpk::_solverName() const { return "LpGlpk"; }
+
+  void LpGlpk::_clear_temporals() {
+    _primal_ray.clear();
+    _dual_ray.clear();
+  }
+
+  LpGlpk::SolveExitStatus LpGlpk::_solve() {
+    return solvePrimal();
+  }
+
+  LpGlpk::SolveExitStatus LpGlpk::solvePrimal() {
+    _clear_temporals();
+
+    glp_smcp smcp;
+    glp_init_smcp(&smcp);
+
+    switch (_message_level) {
+    case MESSAGE_NO_OUTPUT:
+      smcp.msg_lev = GLP_MSG_OFF;
+      break;
+    case MESSAGE_ERROR_MESSAGE:
+      smcp.msg_lev = GLP_MSG_ERR;
+      break;
+    case MESSAGE_NORMAL_OUTPUT:
+      smcp.msg_lev = GLP_MSG_ON;
+      break;
+    case MESSAGE_FULL_OUTPUT:
+      smcp.msg_lev = GLP_MSG_ALL;
+      break;
+    }
+
+    if (glp_simplex(lp, &smcp) != 0) return UNSOLVED;
+    return SOLVED;
+  }
+
+  LpGlpk::SolveExitStatus LpGlpk::solveDual() {
+    _clear_temporals();
+
+    glp_smcp smcp;
+    glp_init_smcp(&smcp);
+
+    switch (_message_level) {
+    case MESSAGE_NO_OUTPUT:
+      smcp.msg_lev = GLP_MSG_OFF;
+      break;
+    case MESSAGE_ERROR_MESSAGE:
+      smcp.msg_lev = GLP_MSG_ERR;
+      break;
+    case MESSAGE_NORMAL_OUTPUT:
+      smcp.msg_lev = GLP_MSG_ON;
+      break;
+    case MESSAGE_FULL_OUTPUT:
+      smcp.msg_lev = GLP_MSG_ALL;
+      break;
+    }
+    smcp.meth = GLP_DUAL;
+
+    if (glp_simplex(lp, &smcp) != 0) return UNSOLVED;
+    return SOLVED;
+  }
+
+  LpGlpk::Value LpGlpk::_getPrimal(int i) const {
+    return glp_get_col_prim(lp, i);
+  }
+
+  LpGlpk::Value LpGlpk::_getDual(int i) const {
+    return glp_get_row_dual(lp, i);
+  }
+
+  LpGlpk::Value LpGlpk::_getPrimalValue() const {
+    return glp_get_obj_val(lp);
+  }
+
+  LpGlpk::VarStatus LpGlpk::_getColStatus(int i) const {
+    switch (glp_get_col_stat(lp, i)) {
+    case GLP_BS:
+      return BASIC;
+    case GLP_UP:
+      return UPPER;
+    case GLP_LO:
+      return LOWER;
+    case GLP_NF:
+      return FREE;
+    case GLP_NS:
+      return FIXED;
+    default:
+      LEMON_ASSERT(false, "Wrong column status");
+      return LpGlpk::VarStatus();
+    }
+  }
+
+  LpGlpk::VarStatus LpGlpk::_getRowStatus(int i) const {
+    switch (glp_get_row_stat(lp, i)) {
+    case GLP_BS:
+      return BASIC;
+    case GLP_UP:
+      return UPPER;
+    case GLP_LO:
+      return LOWER;
+    case GLP_NF:
+      return FREE;
+    case GLP_NS:
+      return FIXED;
+    default:
+      LEMON_ASSERT(false, "Wrong row status");
+      return LpGlpk::VarStatus();
+    }
+  }
+
+  LpGlpk::Value LpGlpk::_getPrimalRay(int i) const {
+    if (_primal_ray.empty()) {
+      int row_num = glp_get_num_rows(lp);
+      int col_num = glp_get_num_cols(lp);
+
+      _primal_ray.resize(col_num + 1, 0.0);
+
+      int index = glp_get_unbnd_ray(lp);
+      if (index != 0) {
+        // The primal ray is found in primal simplex second phase
+        LEMON_ASSERT((index <= row_num ? glp_get_row_stat(lp, index) :
+                      glp_get_col_stat(lp, index - row_num)) != GLP_BS,
+                     "Wrong primal ray");
+
+        bool negate = glp_get_obj_dir(lp) == GLP_MAX;
+
+        if (index > row_num) {
+          _primal_ray[index - row_num] = 1.0;
+          if (glp_get_col_dual(lp, index - row_num) > 0) {
+            negate = !negate;
+          }
+        } else {
+          if (glp_get_row_dual(lp, index) > 0) {
+            negate = !negate;
+          }
         }
-        else{
-          LEMON_glp(set_row_bnds)(lp, i, LEMON_GLP(DB), lb, ub);
+
+        std::vector<int> ray_indexes(row_num + 1);
+        std::vector<Value> ray_values(row_num + 1);
+        int ray_length = glp_eval_tab_col(lp, index, &ray_indexes.front(),
+                                          &ray_values.front());
+
+        for (int i = 1; i <= ray_length; ++i) {
+          if (ray_indexes[i] > row_num) {
+            _primal_ray[ray_indexes[i] - row_num] = ray_values[i];
+          }
         }
-      }
-    }
-
-    solved = false;
-  }
-
-  void LpGlpk::_getRowBounds(int i, Value &lb, Value &ub) const
-  {
-
-    int b=LEMON_glp(get_row_type)(lp, i);
-    switch (b) {
-    case LEMON_GLP(FR):
-    case LEMON_GLP(UP):
-      lb = -INF;
-        break;
+
+        if (negate) {
+          for (int i = 1; i <= col_num; ++i) {
+            _primal_ray[i] = - _primal_ray[i];
+          }
+        }
+      } else {
+        for (int i = 1; i <= col_num; ++i) {
+          _primal_ray[i] = glp_get_col_prim(lp, i);
+        }
+      }
+    }
+    return _primal_ray[i];
+  }
+
+  LpGlpk::Value LpGlpk::_getDualRay(int i) const {
+    if (_dual_ray.empty()) {
+      int row_num = glp_get_num_rows(lp);
+
+      _dual_ray.resize(row_num + 1, 0.0);
+
+      int index = glp_get_unbnd_ray(lp);
+      if (index != 0) {
+        // The dual ray is found in dual simplex second phase
+        LEMON_ASSERT((index <= row_num ? glp_get_row_stat(lp, index) :
+                      glp_get_col_stat(lp, index - row_num)) == GLP_BS,
+
+                     "Wrong dual ray");
+
+        int idx;
+        bool negate = false;
+
+        if (index > row_num) {
+          idx = glp_get_col_bind(lp, index - row_num);
+          if (glp_get_col_prim(lp, index - row_num) >
+              glp_get_col_ub(lp, index - row_num)) {
+            negate = true;
+          }
+        } else {
+          idx = glp_get_row_bind(lp, index);
+          if (glp_get_row_prim(lp, index) > glp_get_row_ub(lp, index)) {
+            negate = true;
+          }
+        }
+
+        _dual_ray[idx] = negate ?  - 1.0 : 1.0;
+
+        glp_btran(lp, &_dual_ray.front());
+      } else {
+        double eps = 1e-7;
+        // The dual ray is found in primal simplex first phase
+        // We assume that the glpk minimizes the slack to get feasible solution
+        for (int i = 1; i <= row_num; ++i) {
+          int index = glp_get_bhead(lp, i);
+          if (index <= row_num) {
+            double res = glp_get_row_prim(lp, index);
+            if (res > glp_get_row_ub(lp, index) + eps) {
+              _dual_ray[i] = -1;
+            } else if (res < glp_get_row_lb(lp, index) - eps) {
+              _dual_ray[i] = 1;
+            } else {
+              _dual_ray[i] = 0;
+            }
+            _dual_ray[i] *= glp_get_rii(lp, index);
+          } else {
+            double res = glp_get_col_prim(lp, index - row_num);
+            if (res > glp_get_col_ub(lp, index - row_num) + eps) {
+              _dual_ray[i] = -1;
+            } else if (res < glp_get_col_lb(lp, index - row_num) - eps) {
+              _dual_ray[i] = 1;
+            } else {
+              _dual_ray[i] = 0;
+            }
+            _dual_ray[i] /= glp_get_sjj(lp, index - row_num);
+          }
+        }
+
+        glp_btran(lp, &_dual_ray.front());
+
+        for (int i = 1; i <= row_num; ++i) {
+          _dual_ray[i] /= glp_get_rii(lp, i);
+        }
+      }
+    }
+    return _dual_ray[i];
+  }
+
+  LpGlpk::ProblemType LpGlpk::_getPrimalType() const {
+    if (glp_get_status(lp) == GLP_OPT)
+      return OPTIMAL;
+    switch (glp_get_prim_stat(lp)) {
+    case GLP_UNDEF:
+      return UNDEFINED;
+    case GLP_FEAS:
+    case GLP_INFEAS:
+      if (glp_get_dual_stat(lp) == GLP_NOFEAS) {
+        return UNBOUNDED;
+      } else {
+        return UNDEFINED;
+      }
+    case GLP_NOFEAS:
+      return INFEASIBLE;
     default:
-      lb=LEMON_glp(get_row_lb)(lp, i);
-    }
-
-    switch (b) {
-    case LEMON_GLP(FR):
-    case LEMON_GLP(LO):
-      ub = INF;
-        break;
+      LEMON_ASSERT(false, "Wrong primal type");
+      return  LpGlpk::ProblemType();
+    }
+  }
+
+  LpGlpk::ProblemType LpGlpk::_getDualType() const {
+    if (glp_get_status(lp) == GLP_OPT)
+      return OPTIMAL;
+    switch (glp_get_dual_stat(lp)) {
+    case GLP_UNDEF:
+      return UNDEFINED;
+    case GLP_FEAS:
+    case GLP_INFEAS:
+      if (glp_get_prim_stat(lp) == GLP_NOFEAS) {
+        return UNBOUNDED;
+      } else {
+        return UNDEFINED;
+      }
+    case GLP_NOFEAS:
+      return INFEASIBLE;
     default:
-      ub=LEMON_glp(get_row_ub)(lp, i);
-    }
-
-  }
-
-  void LpGlpk::_setObjCoeff(int i, Value obj_coef)
-  {
-    //i=0 means the constant term (shift)
-    LEMON_glp(set_obj_coef)(lp, i, obj_coef);
-
-    solved = false;
-  }
-
-  LpGlpk::Value LpGlpk::_getObjCoeff(int i) const {
-    //i=0 means the constant term (shift)
-    return LEMON_glp(get_obj_coef)(lp, i);
-  }
-
-  void LpGlpk::_clearObj()
-  {
-    for (int i=0;i<=LEMON_glp(get_num_cols)(lp);++i){
-      LEMON_glp(set_obj_coef)(lp, i, 0);
-    }
-
-    solved = false;
-  }
-
-  LpGlpk::SolveExitStatus LpGlpk::_solve()
-  {
-    // A way to check the problem to be solved
-    //LEMON_glp(write_cpxlp(lp,"naittvan.cpx");
-
-    LEMON_lpx(std_basis)(lp);
-    int i =  LEMON_lpx(simplex)(lp);
-
-    switch (i) {
-    case LEMON_LPX(E_OK):
-      solved = true;
-      return SOLVED;
+      LEMON_ASSERT(false, "Wrong primal type");
+      return  LpGlpk::ProblemType();
+    }
+  }
+
+  void LpGlpk::presolver(bool b) {
+    lpx_set_int_parm(lp, LPX_K_PRESOL, b ? 1 : 0);
+  }
+
+  void LpGlpk::messageLevel(MessageLevel m) {
+    _message_level = m;
+  }
+
+  // MipGlpk members
+
+  MipGlpk::MipGlpk()
+    : LpBase(), GlpkBase(), MipSolver() {
+    messageLevel(MESSAGE_NO_OUTPUT);
+  }
+
+  MipGlpk::MipGlpk(const MipGlpk& other)
+    : LpBase(), GlpkBase(other), MipSolver() {
+    messageLevel(MESSAGE_NO_OUTPUT);
+  }
+
+  void MipGlpk::_setColType(int i, MipGlpk::ColTypes col_type) {
+    switch (col_type) {
+    case INTEGER:
+      glp_set_col_kind(lp, i, GLP_IV);
+      break;
+    case REAL:
+      glp_set_col_kind(lp, i, GLP_CV);
+      break;
+    }
+  }
+
+  MipGlpk::ColTypes MipGlpk::_getColType(int i) const {
+    switch (glp_get_col_kind(lp, i)) {
+    case GLP_IV:
+    case GLP_BV:
+      return INTEGER;
     default:
-      return UNSOLVED;
-    }
-  }
-
-  LpGlpk::Value LpGlpk::_getPrimal(int i) const
-  {
-    return LEMON_glp(get_col_prim)(lp,i);
-  }
-
-  LpGlpk::Value LpGlpk::_getDual(int i) const
-  {
-    return LEMON_glp(get_row_dual)(lp,i);
-  }
-
-  LpGlpk::Value LpGlpk::_getPrimalValue() const
-  {
-    return LEMON_glp(get_obj_val)(lp);
-  }
-  bool LpGlpk::_isBasicCol(int i) const
-  {
-    return (LEMON_glp(get_col_stat)(lp, i)==LEMON_GLP(BS));
-  }
-
-
-  LpGlpk::SolutionStatus LpGlpk::_getPrimalStatus() const
-  {
-    if (!solved) return UNDEFINED;
-    int stat=  LEMON_lpx(get_status)(lp);
-    switch (stat) {
-    case LEMON_LPX(UNDEF)://Undefined (no solve has been run yet)
-      return UNDEFINED;
-    case LEMON_LPX(NOFEAS)://There is no feasible solution (primal, I guess)
-    case LEMON_LPX(INFEAS)://Infeasible
-      return INFEASIBLE;
-    case LEMON_LPX(UNBND)://Unbounded
-      return INFINITE;
-    case LEMON_LPX(FEAS)://Feasible
-      return FEASIBLE;
-    case LEMON_LPX(OPT)://Feasible
-      return OPTIMAL;
-    default:
-      return UNDEFINED; //to avoid gcc warning
-      //FIXME error
-    }
-  }
-
-  LpGlpk::SolutionStatus LpGlpk::_getDualStatus() const
-  {
-    if (!solved) return UNDEFINED;
-    switch (LEMON_lpx(get_dual_stat)(lp)) {
-    case LEMON_LPX(D_UNDEF)://Undefined (no solve has been run yet)
-      return UNDEFINED;
-    case LEMON_LPX(D_NOFEAS)://There is no dual feasible solution
-//    case LEMON_LPX(D_INFEAS://Infeasible
-      return INFEASIBLE;
-    case LEMON_LPX(D_FEAS)://Feasible
-      switch (LEMON_lpx(get_status)(lp)) {
-      case LEMON_LPX(NOFEAS):
-        return INFINITE;
-      case LEMON_LPX(OPT):
+      return REAL;
+    }
+
+  }
+
+  MipGlpk::SolveExitStatus MipGlpk::_solve() {
+    glp_smcp smcp;
+    glp_init_smcp(&smcp);
+
+    switch (_message_level) {
+    case MESSAGE_NO_OUTPUT:
+      smcp.msg_lev = GLP_MSG_OFF;
+      break;
+    case MESSAGE_ERROR_MESSAGE:
+      smcp.msg_lev = GLP_MSG_ERR;
+      break;
+    case MESSAGE_NORMAL_OUTPUT:
+      smcp.msg_lev = GLP_MSG_ON;
+      break;
+    case MESSAGE_FULL_OUTPUT:
+      smcp.msg_lev = GLP_MSG_ALL;
+      break;
+    }
+    smcp.meth = GLP_DUAL;
+
+    if (glp_simplex(lp, &smcp) != 0) return UNSOLVED;
+    if (glp_get_status(lp) != GLP_OPT) return SOLVED;
+
+    glp_iocp iocp;
+    glp_init_iocp(&iocp);
+
+    switch (_message_level) {
+    case MESSAGE_NO_OUTPUT:
+      iocp.msg_lev = GLP_MSG_OFF;
+      break;
+    case MESSAGE_ERROR_MESSAGE:
+      iocp.msg_lev = GLP_MSG_ERR;
+      break;
+    case MESSAGE_NORMAL_OUTPUT:
+      iocp.msg_lev = GLP_MSG_ON;
+      break;
+    case MESSAGE_FULL_OUTPUT:
+      iocp.msg_lev = GLP_MSG_ALL;
+      break;
+    }
+
+    if (glp_intopt(lp, &iocp) != 0) return UNSOLVED;
+    return SOLVED;
+  }
+
+
+  MipGlpk::ProblemType MipGlpk::_getType() const {
+    switch (glp_get_status(lp)) {
+    case GLP_OPT:
+      switch (glp_mip_status(lp)) {
+      case GLP_UNDEF:
+        return UNDEFINED;
+      case GLP_NOFEAS:
+        return INFEASIBLE;
+      case GLP_FEAS:
+        return FEASIBLE;
+      case GLP_OPT:
         return OPTIMAL;
       default:
-        return FEASIBLE;
+        LEMON_ASSERT(false, "Wrong problem type.");
+        return MipGlpk::ProblemType();
+      }
+    case GLP_NOFEAS:
+      return INFEASIBLE;
+    case GLP_INFEAS:
+    case GLP_FEAS:
+      if (glp_get_dual_stat(lp) == GLP_NOFEAS) {
+        return UNBOUNDED;
+      } else {
+        return UNDEFINED;
       }
     default:
-      return UNDEFINED; //to avoid gcc warning
-      //FIXME error
-    }
-  }
-
-  LpGlpk::ProblemTypes LpGlpk::_getProblemType() const
-  {
-    if (!solved) return UNKNOWN;
-      //int stat=  LEMON_glp(get_status(lp);
-    int statp=  LEMON_lpx(get_prim_stat)(lp);
-    int statd=  LEMON_lpx(get_dual_stat)(lp);
-    if (statp==LEMON_LPX(P_FEAS) && statd==LEMON_LPX(D_FEAS))
-        return PRIMAL_DUAL_FEASIBLE;
-    if (statp==LEMON_LPX(P_FEAS) && statd==LEMON_LPX(D_NOFEAS))
-        return PRIMAL_FEASIBLE_DUAL_INFEASIBLE;
-    if (statp==LEMON_LPX(P_NOFEAS) && statd==LEMON_LPX(D_FEAS))
-        return PRIMAL_INFEASIBLE_DUAL_FEASIBLE;
-    if (statp==LEMON_LPX(P_NOFEAS) && statd==LEMON_LPX(D_NOFEAS))
-        return PRIMAL_DUAL_INFEASIBLE;
-    //In all other cases
-    return UNKNOWN;
-  }
-
-  void LpGlpk::_setMax()
-  {
-    solved = false;
-    LEMON_glp(set_obj_dir)(lp, LEMON_GLP(MAX));
-  }
-
-  void LpGlpk::_setMin()
-  {
-    solved = false;
-    LEMON_glp(set_obj_dir)(lp, LEMON_GLP(MIN));
-  }
-
-  bool LpGlpk::_isMax() const
-  {
-    return (LEMON_glp(get_obj_dir)(lp)==LEMON_GLP(MAX));
-  }
-
-
-
-  void LpGlpk::messageLevel(int m)
-  {
-    LEMON_lpx(set_int_parm)(lp, LEMON_LPX(K_MSGLEV), m);
-  }
-
-  void LpGlpk::presolver(bool b)
-  {
-    LEMON_lpx(set_int_parm)(lp, LEMON_LPX(K_PRESOL), b);
-  }
-
+      LEMON_ASSERT(false, "Wrong problem type.");
+      return MipGlpk::ProblemType();
+    }
+  }
+
+  MipGlpk::Value MipGlpk::_getSol(int i) const {
+    return glp_mip_col_val(lp, i);
+  }
+
+  MipGlpk::Value MipGlpk::_getSolValue() const {
+    return glp_mip_obj_val(lp);
+  }
+
+  MipGlpk* MipGlpk::_newSolver() const { return new MipGlpk; }
+  MipGlpk* MipGlpk::_cloneSolver() const {return new MipGlpk(*this); }
+
+  const char* MipGlpk::_solverName() const { return "MipGlpk"; }
+
+  void MipGlpk::messageLevel(MessageLevel m) {
+    _message_level = m;
+  }
 
 } //END OF NAMESPACE LEMON
Index: lemon/lp_glpk.h
===================================================================
--- lemon/lp_glpk.h	(revision 458)
+++ lemon/lp_glpk.h	(revision 459)
@@ -36,86 +36,135 @@
 
 
+  /// \brief Base interface for the GLPK LP and MIP solver
+  ///
+  /// This class implements the common interface of the GLPK LP and MIP solver.
+  /// \ingroup lp_group
+  class GlpkBase : virtual public LpBase {
+  protected:
+
+    typedef glp_prob LPX;
+    glp_prob* lp;
+
+    GlpkBase();
+    GlpkBase(const GlpkBase&);
+    virtual ~GlpkBase();
+
+  protected:
+
+    virtual int _addCol();
+    virtual int _addRow();
+
+    virtual void _eraseCol(int i);
+    virtual void _eraseRow(int i);
+
+    virtual void _eraseColId(int i);
+    virtual void _eraseRowId(int i);
+
+    virtual void _getColName(int col, std::string& name) const;
+    virtual void _setColName(int col, const std::string& name);
+    virtual int _colByName(const std::string& name) const;
+
+    virtual void _getRowName(int row, std::string& name) const;
+    virtual void _setRowName(int row, const std::string& name);
+    virtual int _rowByName(const std::string& name) const;
+
+    virtual void _setRowCoeffs(int i, ExprIterator b, ExprIterator e);
+    virtual void _getRowCoeffs(int i, InsertIterator b) const;
+
+    virtual void _setColCoeffs(int i, ExprIterator b, ExprIterator e);
+    virtual void _getColCoeffs(int i, InsertIterator b) const;
+
+    virtual void _setCoeff(int row, int col, Value value);
+    virtual Value _getCoeff(int row, int col) const;
+
+    virtual void _setColLowerBound(int i, Value value);
+    virtual Value _getColLowerBound(int i) const;
+
+    virtual void _setColUpperBound(int i, Value value);
+    virtual Value _getColUpperBound(int i) const;
+
+    virtual void _setRowLowerBound(int i, Value value);
+    virtual Value _getRowLowerBound(int i) const;
+
+    virtual void _setRowUpperBound(int i, Value value);
+    virtual Value _getRowUpperBound(int i) const;
+
+    virtual void _setObjCoeffs(ExprIterator b, ExprIterator e);
+    virtual void _getObjCoeffs(InsertIterator b) const;
+
+    virtual void _setObjCoeff(int i, Value obj_coef);
+    virtual Value _getObjCoeff(int i) const;
+
+    virtual void _setSense(Sense);
+    virtual Sense _getSense() const;
+
+    virtual void _clear();
+
+  public:
+
+    ///Pointer to the underlying GLPK data structure.
+    LPX *lpx() {return lp;}
+    ///Const pointer to the underlying GLPK data structure.
+    const LPX *lpx() const {return lp;}
+
+    ///Returns the constraint identifier understood by GLPK.
+    int lpxRow(Row r) const { return rows(id(r)); }
+
+    ///Returns the variable identifier understood by GLPK.
+    int lpxCol(Col c) const { return cols(id(c)); }
+
+  };
+
   /// \brief Interface for the GLPK LP solver
   ///
   /// This class implements an interface for the GLPK LP solver.
   ///\ingroup lp_group
-  class LpGlpk : virtual public LpSolverBase {
-  protected:
-
-    typedef glp_prob LPX;
-    glp_prob* lp;
-    bool solved;
-
-  public:
-
-    typedef LpSolverBase Parent;
-
+  class LpGlpk : public GlpkBase, public LpSolver {
+  public:
+
+    ///\e
     LpGlpk();
-    LpGlpk(const LpGlpk &);
-    ~LpGlpk();
-
-  protected:
-    virtual LpSolverBase* _newLp();
-    virtual LpSolverBase* _copyLp();
-
-    virtual int _addCol();
-    virtual int _addRow();
-    virtual void _eraseCol(int i);
-    virtual void _eraseRow(int i);
-    virtual void _getColName(int col, std::string & name) const;
-    virtual void _setColName(int col, const std::string & name);
-    virtual int _colByName(const std::string& name) const;
-    virtual void _setRowCoeffs(int i, ConstRowIterator b, ConstRowIterator e);
-    virtual void _getRowCoeffs(int i, RowIterator b) const;
-    virtual void _setColCoeffs(int i, ConstColIterator b, ConstColIterator e);
-    virtual void _getColCoeffs(int i, ColIterator b) const;
-    virtual void _setCoeff(int row, int col, Value value);
-    virtual Value _getCoeff(int row, int col) const;
-
-    virtual void _setColLowerBound(int i, Value value);
-    virtual Value _getColLowerBound(int i) const;
-    virtual void _setColUpperBound(int i, Value value);
-    virtual Value _getColUpperBound(int i) const;
-
-    virtual void _setRowBounds(int i, Value lower, Value upper);
-    virtual void _getRowBounds(int i, Value &lb, Value &ub) const;
-    virtual void _setObjCoeff(int i, Value obj_coef);
-    virtual Value _getObjCoeff(int i) const;
-    virtual void _clearObj();
-
-    ///\e
-
-    ///\todo It should be clarified
-    ///
+    ///\e
+    LpGlpk(const LpGlpk&);
+
+  private:
+
+    mutable std::vector<double> _primal_ray;
+    mutable std::vector<double> _dual_ray;
+
+    void _clear_temporals();
+
+  protected:
+
+    virtual LpGlpk* _cloneSolver() const;
+    virtual LpGlpk* _newSolver() const;
+
+    virtual const char* _solverName() const;
+
     virtual SolveExitStatus _solve();
     virtual Value _getPrimal(int i) const;
     virtual Value _getDual(int i) const;
+
     virtual Value _getPrimalValue() const;
-    virtual bool _isBasicCol(int i) const;
-    ///\e
+
+    virtual VarStatus _getColStatus(int i) const;
+    virtual VarStatus _getRowStatus(int i) const;
+
+    virtual Value _getPrimalRay(int i) const;
+    virtual Value _getDualRay(int i) const;
 
     ///\todo It should be clarified
     ///
-    virtual SolutionStatus _getPrimalStatus() const;
-    virtual SolutionStatus _getDualStatus() const;
-    virtual ProblemTypes _getProblemType() const;
-
-    virtual void _setMax();
-    virtual void _setMin();
-
-    virtual bool _isMax() const;
-
-  public:
-    ///Set the verbosity of the messages
-
-    ///Set the verbosity of the messages
-    ///
-    ///\param m is the level of the messages output by the solver routines.
-    ///The possible values are:
-    ///- 0 --- no output (default value)
-    ///- 1 --- error messages only
-    ///- 2 --- normal output
-    ///- 3 --- full output (includes informational messages)
-    void messageLevel(int m);
+    virtual ProblemType _getPrimalType() const;
+    virtual ProblemType _getDualType() const;
+
+  public:
+
+    ///Solve with primal simplex
+    SolveExitStatus solvePrimal();
+
+    ///Solve with dual simplex
+    SolveExitStatus solveDual();
+
     ///Turns on or off the presolver
 
@@ -125,13 +174,84 @@
     void presolver(bool b);
 
-    ///Pointer to the underlying GLPK data structure.
-    LPX *lpx() {return lp;}
-
-    ///Returns the constraint identifier understood by GLPK.
-    int lpxRow(Row r) { return _lpId(r); }
-
-    ///Returns the variable identifier understood by GLPK.
-    int lpxCol(Col c) { return _lpId(c); }
+    ///Enum for \c messageLevel() parameter
+    enum MessageLevel {
+      /// no output (default value)
+      MESSAGE_NO_OUTPUT = 0,
+      /// error messages only
+      MESSAGE_ERROR_MESSAGE = 1,
+      /// normal output
+      MESSAGE_NORMAL_OUTPUT = 2,
+      /// full output (includes informational messages)
+      MESSAGE_FULL_OUTPUT = 3
+    };
+
+  private:
+
+    MessageLevel _message_level;
+
+  public:
+
+    ///Set the verbosity of the messages
+
+    ///Set the verbosity of the messages
+    ///
+    ///\param m is the level of the messages output by the solver routines.
+    void messageLevel(MessageLevel m);
   };
+
+  /// \brief Interface for the GLPK MIP solver
+  ///
+  /// This class implements an interface for the GLPK MIP solver.
+  ///\ingroup lp_group
+  class MipGlpk : public GlpkBase, public MipSolver {
+  public:
+
+    ///\e
+    MipGlpk();
+    ///\e
+    MipGlpk(const MipGlpk&);
+
+  protected:
+
+    virtual MipGlpk* _cloneSolver() const;
+    virtual MipGlpk* _newSolver() const;
+
+    virtual const char* _solverName() const;
+
+    virtual ColTypes _getColType(int col) const;
+    virtual void _setColType(int col, ColTypes col_type);
+
+    virtual SolveExitStatus _solve();
+    virtual ProblemType _getType() const;
+    virtual Value _getSol(int i) const;
+    virtual Value _getSolValue() const;
+
+    ///Enum for \c messageLevel() parameter
+    enum MessageLevel {
+      /// no output (default value)
+      MESSAGE_NO_OUTPUT = 0,
+      /// error messages only
+      MESSAGE_ERROR_MESSAGE = 1,
+      /// normal output
+      MESSAGE_NORMAL_OUTPUT = 2,
+      /// full output (includes informational messages)
+      MESSAGE_FULL_OUTPUT = 3
+    };
+
+  private:
+
+    MessageLevel _message_level;
+
+  public:
+
+    ///Set the verbosity of the messages
+
+    ///Set the verbosity of the messages
+    ///
+    ///\param m is the level of the messages output by the solver routines.
+    void messageLevel(MessageLevel m);
+  };
+
+
 } //END OF NAMESPACE LEMON
 
Index: lemon/lp_skeleton.cc
===================================================================
--- lemon/lp_skeleton.cc	(revision 458)
+++ lemon/lp_skeleton.cc	(revision 459)
@@ -23,164 +23,111 @@
 namespace lemon {
 
-  LpSolverBase* LpSkeleton::_newLp()
-  {
-    LpSolverBase *tmp=0;
-    return tmp;
-  }
-
-  LpSolverBase* LpSkeleton::_copyLp()
-  {
-    LpSolverBase *tmp=0;
-    return tmp;
-  }
-
-  int LpSkeleton::_addCol()
+  int SkeletonSolverBase::_addCol()
   {
     return ++col_num;
   }
 
-  int LpSkeleton::_addRow()
+  int SkeletonSolverBase::_addRow()
   {
     return ++row_num;
   }
 
-  void LpSkeleton::_eraseCol(int ) {
+  void SkeletonSolverBase::_eraseCol(int) {}
+  void SkeletonSolverBase::_eraseRow(int) {}
+
+  void SkeletonSolverBase::_getColName(int, std::string &) const {}
+  void SkeletonSolverBase::_setColName(int, const std::string &) {}
+  int SkeletonSolverBase::_colByName(const std::string&) const { return -1; }
+
+  void SkeletonSolverBase::_getRowName(int, std::string &) const {}
+  void SkeletonSolverBase::_setRowName(int, const std::string &) {}
+  int SkeletonSolverBase::_rowByName(const std::string&) const { return -1; }
+
+  void SkeletonSolverBase::_setRowCoeffs(int, ExprIterator, ExprIterator) {}
+  void SkeletonSolverBase::_getRowCoeffs(int, InsertIterator) const {}
+
+  void SkeletonSolverBase::_setColCoeffs(int, ExprIterator, ExprIterator) {}
+  void SkeletonSolverBase::_getColCoeffs(int, InsertIterator) const {}
+
+  void SkeletonSolverBase::_setCoeff(int, int, Value) {}
+  SkeletonSolverBase::Value SkeletonSolverBase::_getCoeff(int, int) const
+  { return 0; }
+
+  void SkeletonSolverBase::_setColLowerBound(int, Value) {}
+  SkeletonSolverBase::Value SkeletonSolverBase::_getColLowerBound(int) const
+  {  return 0; }
+
+  void SkeletonSolverBase::_setColUpperBound(int, Value) {}
+  SkeletonSolverBase::Value SkeletonSolverBase::_getColUpperBound(int) const
+  {  return 0; }
+
+  void SkeletonSolverBase::_setRowLowerBound(int, Value) {}
+  SkeletonSolverBase::Value SkeletonSolverBase::_getRowLowerBound(int) const
+  {  return 0; }
+
+  void SkeletonSolverBase::_setRowUpperBound(int, Value) {}
+  SkeletonSolverBase::Value SkeletonSolverBase::_getRowUpperBound(int) const
+  {  return 0; }
+
+  void SkeletonSolverBase::_setObjCoeffs(ExprIterator, ExprIterator) {}
+  void SkeletonSolverBase::_getObjCoeffs(InsertIterator) const {};
+
+  void SkeletonSolverBase::_setObjCoeff(int, Value) {}
+  SkeletonSolverBase::Value SkeletonSolverBase::_getObjCoeff(int) const
+  {  return 0; }
+
+  void SkeletonSolverBase::_setSense(Sense) {}
+  SkeletonSolverBase::Sense SkeletonSolverBase::_getSense() const
+  { return MIN; }
+
+  void SkeletonSolverBase::_clear() {
+    row_num = col_num = 0;
   }
 
-  void LpSkeleton::_eraseRow(int) {
-  }
+  LpSkeleton::SolveExitStatus LpSkeleton::_solve() { return SOLVED; }
 
-  void LpSkeleton::_getColName(int, std::string &) const {
-  }
+  LpSkeleton::Value LpSkeleton::_getPrimal(int) const { return 0; }
+  LpSkeleton::Value LpSkeleton::_getDual(int) const { return 0; }
+  LpSkeleton::Value LpSkeleton::_getPrimalValue() const { return 0; }
 
+  LpSkeleton::Value LpSkeleton::_getPrimalRay(int) const { return 0; }
+  LpSkeleton::Value LpSkeleton::_getDualRay(int) const { return 0; }
 
-  void LpSkeleton::_setColName(int, const std::string &) {
-  }
+  LpSkeleton::ProblemType LpSkeleton::_getPrimalType() const
+  { return UNDEFINED; }
 
-  int LpSkeleton::_colByName(const std::string&) const { return -1; }
+  LpSkeleton::ProblemType LpSkeleton::_getDualType() const
+  { return UNDEFINED; }
 
+  LpSkeleton::VarStatus LpSkeleton::_getColStatus(int) const
+  { return BASIC; }
 
-  void LpSkeleton::_setRowCoeffs(int, ConstRowIterator, ConstRowIterator) {
-  }
+  LpSkeleton::VarStatus LpSkeleton::_getRowStatus(int) const
+  { return BASIC; }
 
-  void LpSkeleton::_getRowCoeffs(int, RowIterator) const {
-  }
+  LpSkeleton* LpSkeleton::_newSolver() const
+  { return static_cast<LpSkeleton*>(0); }
 
-  void LpSkeleton::_setColCoeffs(int, ConstColIterator, ConstColIterator) {
-  }
+  LpSkeleton* LpSkeleton::_cloneSolver() const
+  { return static_cast<LpSkeleton*>(0); }
 
-  void LpSkeleton::_getColCoeffs(int, ColIterator) const {
-  }
+  const char* LpSkeleton::_solverName() const { return "LpSkeleton"; }
 
-  void LpSkeleton::_setCoeff(int, int, Value )
-  {
-  }
+  MipSkeleton::SolveExitStatus MipSkeleton::_solve()
+  { return SOLVED; }
 
-  LpSkeleton::Value LpSkeleton::_getCoeff(int, int) const
-  {
-    return 0;
-  }
+  MipSkeleton::Value MipSkeleton::_getSol(int) const { return 0; }
+  MipSkeleton::Value MipSkeleton::_getSolValue() const { return 0; }
 
+  MipSkeleton::ProblemType MipSkeleton::_getType() const
+  { return UNDEFINED; }
 
-  void LpSkeleton::_setColLowerBound(int, Value)
-  {
-  }
+  MipSkeleton* MipSkeleton::_newSolver() const
+  { return static_cast<MipSkeleton*>(0); }
 
-  LpSkeleton::Value LpSkeleton::_getColLowerBound(int) const
-  {
-    return 0;
-  }
+  MipSkeleton* MipSkeleton::_cloneSolver() const
+  { return static_cast<MipSkeleton*>(0); }
 
-  void LpSkeleton::_setColUpperBound(int, Value)
-  {
-  }
-
-  LpSkeleton::Value LpSkeleton::_getColUpperBound(int) const
-  {
-    return 0;
-  }
-
-//   void LpSkeleton::_setRowLowerBound(int, Value)
-//   {
-//   }
-
-//   void LpSkeleton::_setRowUpperBound(int, Value)
-//   {
-//   }
-
-  void LpSkeleton::_setRowBounds(int, Value, Value)
-  {
-  }
-
-  void LpSkeleton::_getRowBounds(int, Value&, Value&) const
-  {
-  }
-
-  void LpSkeleton::_setObjCoeff(int, Value)
-  {
-  }
-
-  LpSkeleton::Value LpSkeleton::_getObjCoeff(int) const
-  {
-    return 0;
-  }
-
-  void LpSkeleton::_setMax()
-  {
-  }
-
-  void LpSkeleton::_setMin()
-  {
-  }
-
-  bool LpSkeleton::_isMax() const
-  {
-    return true;
-  }
-
-
-  void LpSkeleton::_clearObj()
-  {
-  }
-
-  LpSkeleton::SolveExitStatus LpSkeleton::_solve()
-  {
-    return SOLVED;
-  }
-
-  LpSkeleton::Value LpSkeleton::_getPrimal(int) const
-  {
-    return 0;
-  }
-
-  LpSkeleton::Value LpSkeleton::_getDual(int) const
-  {
-    return 0;
-  }
-
-  LpSkeleton::Value LpSkeleton::_getPrimalValue() const
-  {
-    return 0;
-  }
-
-  LpSkeleton::SolutionStatus LpSkeleton::_getPrimalStatus() const
-  {
-    return UNDEFINED;
-  }
-
-  LpSkeleton::SolutionStatus LpSkeleton::_getDualStatus() const
-  {
-    return UNDEFINED;
-  }
-
-  LpSkeleton::ProblemTypes LpSkeleton::_getProblemType() const
-  {
-    return UNKNOWN;
-  }
-
-  bool LpSkeleton::_isBasicCol(int) const
-  {
-    return true;
-  }
+  const char* MipSkeleton::_solverName() const { return "MipSkeleton"; }
 
 } //namespace lemon
Index: lemon/lp_skeleton.h
===================================================================
--- lemon/lp_skeleton.h	(revision 458)
+++ lemon/lp_skeleton.h	(revision 459)
@@ -27,13 +27,12 @@
 
   ///A skeleton class to implement LP solver interfaces
-  class LpSkeleton :public LpSolverBase {
+  class SkeletonSolverBase : public virtual LpBase {
     int col_num,row_num;
 
   protected:
 
-    ///\e
-    virtual LpSolverBase* _newLp();
-    ///\e
-    virtual LpSolverBase* _copyLp();
+    SkeletonSolverBase()
+      : col_num(-1), row_num(-1) {}
+
     /// \e
     virtual int _addCol();
@@ -44,19 +43,27 @@
     /// \e
     virtual void _eraseRow(int i);
-    /// \e
-    virtual void _getColName(int col, std::string & name) const;
-    /// \e
-    virtual void _setColName(int col, const std::string & name);
+
+    /// \e
+    virtual void _getColName(int col, std::string& name) const;
+    /// \e
+    virtual void _setColName(int col, const std::string& name);
     /// \e
     virtual int _colByName(const std::string& name) const;
 
     /// \e
-    virtual void _setRowCoeffs(int i, ConstRowIterator b, ConstRowIterator e);
-    /// \e
-    virtual void _getRowCoeffs(int i, RowIterator b) const;
-    /// \e
-    virtual void _setColCoeffs(int i, ConstColIterator b, ConstColIterator e);
-    /// \e
-    virtual void _getColCoeffs(int i, ColIterator b) const;
+    virtual void _getRowName(int row, std::string& name) const;
+    /// \e
+    virtual void _setRowName(int row, const std::string& name);
+    /// \e
+    virtual int _rowByName(const std::string& name) const;
+
+    /// \e
+    virtual void _setRowCoeffs(int i, ExprIterator b, ExprIterator e);
+    /// \e
+    virtual void _getRowCoeffs(int i, InsertIterator b) const;
+    /// \e
+    virtual void _setColCoeffs(int i, ExprIterator b, ExprIterator e);
+    /// \e
+    virtual void _getColCoeffs(int i, InsertIterator b) const;
 
     /// Set one element of the coefficient matrix
@@ -88,93 +95,132 @@
     virtual Value _getColUpperBound(int i) const;
 
-//     /// The lower bound of a linear expression (row) have to be given by an
-//     /// extended number of type Value, i.e. a finite number of type
-//     /// Value or -\ref INF.
-//     virtual void _setRowLowerBound(int i, Value value);
-//     /// \e
-
-//     /// The upper bound of a linear expression (row) have to be given by an
-//     /// extended number of type Value, i.e. a finite number of type
-//     /// Value or \ref INF.
-//     virtual void _setRowUpperBound(int i, Value value);
-
-    /// The lower and upper bound of a linear expression (row) have to be
-    /// given by an
-    /// extended number of type Value, i.e. a finite number of type
-    /// Value or +/-\ref INF.
-    virtual void _setRowBounds(int i, Value lb, Value ub);
-    /// \e
-
-
-    /// The lower and the upper bound of
-    /// a constraint (row) are
-    /// extended numbers of type Value, i.e.  finite numbers of type
-    /// Value, -\ref INF or \ref INF.
-    virtual void _getRowBounds(int i, Value &lb, Value &ub) const;
-    /// \e
-
-
-    /// \e
-    virtual void _clearObj();
+    /// The lower bound of a constraint (row) have to be given by an
+    /// extended number of type Value, i.e. a finite number of type
+    /// Value or -\ref INF.
+    virtual void _setRowLowerBound(int i, Value value);
+    /// \e
+
+    /// The lower bound of a constraint (row) is an
+    /// extended number of type Value, i.e. a finite number of type
+    /// Value or -\ref INF.
+    virtual Value _getRowLowerBound(int i) const;
+
+    /// The upper bound of a constraint (row) have to be given by an
+    /// extended number of type Value, i.e. a finite number of type
+    /// Value or \ref INF.
+    virtual void _setRowUpperBound(int i, Value value);
+    /// \e
+
+    /// The upper bound of a constraint (row) is an
+    /// extended number of type Value, i.e. a finite number of type
+    /// Value or \ref INF.
+    virtual Value _getRowUpperBound(int i) const;
+
+    /// \e
+    virtual void _setObjCoeffs(ExprIterator b, ExprIterator e);
+    /// \e
+    virtual void _getObjCoeffs(InsertIterator b) const;
+
     /// \e
     virtual void _setObjCoeff(int i, Value obj_coef);
-
     /// \e
     virtual Value _getObjCoeff(int i) const;
 
     ///\e
-
-    ///\bug Wrong interface
-    ///
+    virtual void _setSense(Sense);
+    ///\e
+    virtual Sense _getSense() const;
+
+    ///\e
+    virtual void _clear();
+
+  };
+
+  /// \brief Interface for a skeleton LP solver
+  ///
+  /// This class implements an interface for a skeleton LP solver.
+  ///\ingroup lp_group
+  class LpSkeleton : public SkeletonSolverBase, public LpSolver {
+  public:
+    LpSkeleton() : SkeletonSolverBase(), LpSolver() {}
+
+  protected:
+
+    ///\e
     virtual SolveExitStatus _solve();
 
     ///\e
-
-    ///\bug Wrong interface
-    ///
     virtual Value _getPrimal(int i) const;
-
-    ///\e
-
-    ///\bug Wrong interface
-    ///
+    ///\e
     virtual Value _getDual(int i) const;
 
     ///\e
-
-    ///\bug Wrong interface
-    ///
     virtual Value _getPrimalValue() const;
 
     ///\e
-
-    ///\bug Wrong interface
-    ///
-    virtual SolutionStatus _getPrimalStatus() const;
-
-    ////e
-    virtual SolutionStatus _getDualStatus() const;
-
-
-    ///\e
-    virtual ProblemTypes _getProblemType() const;
-
-    ///\e
-    virtual void _setMax();
-    ///\e
-    virtual void _setMin();
-
-    ///\e
-    virtual bool _isMax() const;
-
-
-
-    ///\e
-    virtual bool _isBasicCol(int i) const;
-
-
-
+    virtual Value _getPrimalRay(int i) const;
+    ///\e
+    virtual Value _getDualRay(int i) const;
+
+    ///\e
+    virtual ProblemType _getPrimalType() const;
+    ///\e
+    virtual ProblemType _getDualType() const;
+
+    ///\e
+    virtual VarStatus _getColStatus(int i) const;
+    ///\e
+    virtual VarStatus _getRowStatus(int i) const;
+
+    ///\e
+    virtual LpSkeleton* _newSolver() const;
+    ///\e
+    virtual LpSkeleton* _cloneSolver() const;
+    ///\e
+    virtual const char* _solverName() const;
+
+  };
+
+  /// \brief Interface for a skeleton MIP solver
+  ///
+  /// This class implements an interface for a skeleton MIP solver.
+  ///\ingroup lp_group
+  class MipSkeleton : public SkeletonSolverBase, public MipSolver {
   public:
-    LpSkeleton() : LpSolverBase(), col_num(0), row_num(0) {}
+    MipSkeleton() : SkeletonSolverBase(), MipSolver() {}
+
+  protected:
+    ///\e
+
+    ///\bug Wrong interface
+    ///
+    virtual SolveExitStatus _solve();
+
+    ///\e
+
+    ///\bug Wrong interface
+    ///
+    virtual Value _getSol(int i) const;
+
+    ///\e
+
+    ///\bug Wrong interface
+    ///
+    virtual Value _getSolValue() const;
+
+    ///\e
+
+    ///\bug Wrong interface
+    ///
+    virtual ProblemType _getType() const;
+
+    ///\e
+    virtual MipSkeleton* _newSolver() const;
+
+    ///\e
+    virtual MipSkeleton* _cloneSolver() const;
+    ///\e
+    virtual const char* _solverName() const;
+
   };
 
Index: lemon/lp_soplex.cc
===================================================================
--- lemon/lp_soplex.cc	(revision 458)
+++ lemon/lp_soplex.cc	(revision 459)
@@ -17,6 +17,6 @@
  */
 
-#include<iostream>
-#include<lemon/lp_soplex.h>
+#include <iostream>
+#include <lemon/lp_soplex.h>
 
 #include <soplex/soplex.h>
@@ -27,9 +27,6 @@
 namespace lemon {
 
-  LpSoplex::LpSoplex() : LpSolverBase() {
-    rows.setIdHandler(relocateIdHandler);
-    cols.setIdHandler(relocateIdHandler);
+  LpSoplex::LpSoplex() {
     soplex = new soplex::SoPlex;
-    solved = false;
   }
 
@@ -38,31 +35,35 @@
   }
 
-  LpSoplex::LpSoplex(const LpSoplex& lp) : LpSolverBase() {
+  LpSoplex::LpSoplex(const LpSoplex& lp) {
     rows = lp.rows;
-    rows.setIdHandler(relocateIdHandler);
-
     cols = lp.cols;
-    cols.setIdHandler(relocateIdHandler);
 
     soplex = new soplex::SoPlex;
     (*static_cast<soplex::SPxLP*>(soplex)) = *(lp.soplex);
 
-    colNames = lp.colNames;
-    invColNames = lp.invColNames;
-
-    primal_value = lp.primal_value;
-    dual_value = lp.dual_value;
-
-  }
-
-  LpSolverBase* LpSoplex::_newLp() {
+    _col_names = lp._col_names;
+    _col_names_ref = lp._col_names_ref;
+
+    _row_names = lp._row_names;
+    _row_names_ref = lp._row_names_ref;
+
+  }
+
+  void LpSoplex::_clear_temporals() {
+    _primal_values.clear();
+    _dual_values.clear();
+  }
+
+  LpSoplex* LpSoplex::_newSolver() const {
     LpSoplex* newlp = new LpSoplex();
     return newlp;
   }
 
-  LpSolverBase* LpSoplex::_copyLp() {
+  LpSoplex* LpSoplex::_cloneSolver() const {
     LpSoplex* newlp = new LpSoplex(*this);
     return newlp;
   }
+
+  const char* LpSoplex::_solverName() const { return "LpSoplex"; }
 
   int LpSoplex::_addCol() {
@@ -72,7 +73,5 @@
     soplex->addCol(c);
 
-    colNames.push_back(std::string());
-    primal_value.push_back(0.0);
-    solved = false;
+    _col_names.push_back(std::string());
 
     return soplex->nCols() - 1;
@@ -85,6 +84,5 @@
     soplex->addRow(r);
 
-    dual_value.push_back(0.0);
-    solved = false;
+    _row_names.push_back(std::string());
 
     return soplex->nRows() - 1;
@@ -94,29 +92,36 @@
   void LpSoplex::_eraseCol(int i) {
     soplex->removeCol(i);
-    invColNames.erase(colNames[i]);
-    colNames[i] = colNames.back();
-    invColNames[colNames.back()] = i;
-    colNames.pop_back();
-    primal_value[i] = primal_value.back();
-    primal_value.pop_back();
-    solved = false;
+    _col_names_ref.erase(_col_names[i]);
+    _col_names[i] = _col_names.back();
+    _col_names_ref[_col_names.back()] = i;
+    _col_names.pop_back();
   }
 
   void LpSoplex::_eraseRow(int i) {
     soplex->removeRow(i);
-    dual_value[i] = dual_value.back();
-    dual_value.pop_back();
-    solved = false;
+    _row_names_ref.erase(_row_names[i]);
+    _row_names[i] = _row_names.back();
+    _row_names_ref[_row_names.back()] = i;
+    _row_names.pop_back();
+  }
+
+  void LpSoplex::_eraseColId(int i) {
+    cols.eraseIndex(i);
+    cols.relocateIndex(i, cols.maxIndex());
+  }
+  void LpSoplex::_eraseRowId(int i) {
+    rows.eraseIndex(i);
+    rows.relocateIndex(i, rows.maxIndex());
   }
 
   void LpSoplex::_getColName(int c, std::string &name) const {
-    name = colNames[c];
+    name = _col_names[c];
   }
 
   void LpSoplex::_setColName(int c, const std::string &name) {
-    invColNames.erase(colNames[c]);
-    colNames[c] = name;
+    _col_names_ref.erase(_col_names[c]);
+    _col_names[c] = name;
     if (!name.empty()) {
-      invColNames.insert(std::make_pair(name, c));
+      _col_names_ref.insert(std::make_pair(name, c));
     }
   }
@@ -124,6 +129,6 @@
   int LpSoplex::_colByName(const std::string& name) const {
     std::map<std::string, int>::const_iterator it =
-      invColNames.find(name);
-    if (it != invColNames.end()) {
+      _col_names_ref.find(name);
+    if (it != _col_names_ref.end()) {
       return it->second;
     } else {
@@ -132,16 +137,37 @@
   }
 
-
-  void LpSoplex::_setRowCoeffs(int i, ConstRowIterator b, ConstRowIterator e) {
+  void LpSoplex::_getRowName(int r, std::string &name) const {
+    name = _row_names[r];
+  }
+
+  void LpSoplex::_setRowName(int r, const std::string &name) {
+    _row_names_ref.erase(_row_names[r]);
+    _row_names[r] = name;
+    if (!name.empty()) {
+      _row_names_ref.insert(std::make_pair(name, r));
+    }
+  }
+
+  int LpSoplex::_rowByName(const std::string& name) const {
+    std::map<std::string, int>::const_iterator it =
+      _row_names_ref.find(name);
+    if (it != _row_names_ref.end()) {
+      return it->second;
+    } else {
+      return -1;
+    }
+  }
+
+
+  void LpSoplex::_setRowCoeffs(int i, ExprIterator b, ExprIterator e) {
     for (int j = 0; j < soplex->nCols(); ++j) {
       soplex->changeElement(i, j, 0.0);
     }
-    for(ConstRowIterator it = b; it != e; ++it) {
+    for(ExprIterator it = b; it != e; ++it) {
       soplex->changeElement(i, it->first, it->second);
     }
-    solved = false;
-  }
-
-  void LpSoplex::_getRowCoeffs(int i, RowIterator b) const {
+  }
+
+  void LpSoplex::_getRowCoeffs(int i, InsertIterator b) const {
     const soplex::SVector& vec = soplex->rowVector(i);
     for (int k = 0; k < vec.size(); ++k) {
@@ -151,15 +177,14 @@
   }
 
-  void LpSoplex::_setColCoeffs(int j, ConstColIterator b, ConstColIterator e) {
+  void LpSoplex::_setColCoeffs(int j, ExprIterator b, ExprIterator e) {
     for (int i = 0; i < soplex->nRows(); ++i) {
       soplex->changeElement(i, j, 0.0);
     }
-    for(ConstColIterator it = b; it != e; ++it) {
+    for(ExprIterator it = b; it != e; ++it) {
       soplex->changeElement(it->first, j, it->second);
     }
-    solved = false;
-  }
-
-  void LpSoplex::_getColCoeffs(int i, ColIterator b) const {
+  }
+
+  void LpSoplex::_getColCoeffs(int i, InsertIterator b) const {
     const soplex::SVector& vec = soplex->colVector(i);
     for (int k = 0; k < vec.size(); ++k) {
@@ -171,5 +196,4 @@
   void LpSoplex::_setCoeff(int i, int j, Value value) {
     soplex->changeElement(i, j, value);
-    solved = false;
   }
 
@@ -179,6 +203,6 @@
 
   void LpSoplex::_setColLowerBound(int i, Value value) {
+    LEMON_ASSERT(value != INF, "Invalid bound");
     soplex->changeLower(i, value != -INF ? value : -soplex::infinity);
-    solved = false;
   }
 
@@ -189,6 +213,6 @@
 
   void LpSoplex::_setColUpperBound(int i, Value value) {
+    LEMON_ASSERT(value != -INF, "Invalid bound");
     soplex->changeUpper(i, value != INF ? value : soplex::infinity);
-    solved = false;
   }
 
@@ -198,19 +222,45 @@
   }
 
-  void LpSoplex::_setRowBounds(int i, Value lb, Value ub) {
-    soplex->changeRange(i, lb != -INF ? lb : -soplex::infinity,
-                        ub != INF ? ub : soplex::infinity);
-    solved = false;
-  }
-  void LpSoplex::_getRowBounds(int i, Value &lower, Value &upper) const {
-    lower = soplex->lhs(i);
-    if (lower == -soplex::infinity) lower = -INF;
-    upper = soplex->rhs(i);
-    if (upper == -soplex::infinity) upper = INF;
+  void LpSoplex::_setRowLowerBound(int i, Value lb) {
+    LEMON_ASSERT(lb != INF, "Invalid bound");
+    soplex->changeRange(i, lb != -INF ? lb : -soplex::infinity, soplex->rhs(i));
+  }
+
+  LpSoplex::Value LpSoplex::_getRowLowerBound(int i) const {
+    double res = soplex->lhs(i);
+    return res == -soplex::infinity ? -INF : res;
+  }
+
+  void LpSoplex::_setRowUpperBound(int i, Value ub) {
+    LEMON_ASSERT(ub != -INF, "Invalid bound");
+    soplex->changeRange(i, soplex->lhs(i), ub != INF ? ub : soplex::infinity);
+  }
+
+  LpSoplex::Value LpSoplex::_getRowUpperBound(int i) const {
+    double res = soplex->rhs(i);
+    return res == soplex::infinity ? INF : res;
+  }
+
+  void LpSoplex::_setObjCoeffs(ExprIterator b, ExprIterator e) {
+    for (int j = 0; j < soplex->nCols(); ++j) {
+      soplex->changeObj(j, 0.0);
+    }
+    for (ExprIterator it = b; it != e; ++it) {
+      soplex->changeObj(it->first, it->second);
+    }
+  }
+
+  void LpSoplex::_getObjCoeffs(InsertIterator b) const {
+    for (int j = 0; j < soplex->nCols(); ++j) {
+      Value coef = soplex->obj(j);
+      if (coef != 0.0) {
+        *b = std::make_pair(j, coef);
+        ++b;
+      }
+    }
   }
 
   void LpSoplex::_setObjCoeff(int i, Value obj_coef) {
     soplex->changeObj(i, obj_coef);
-    solved = false;
   }
 
@@ -219,19 +269,9 @@
   }
 
-  void LpSoplex::_clearObj() {
-    for (int i = 0; i < soplex->nCols(); ++i) {
-      soplex->changeObj(i, 0.0);
-    }
-    solved = false;
-  }
-
   LpSoplex::SolveExitStatus LpSoplex::_solve() {
+
+    _clear_temporals();
+
     soplex::SPxSolver::Status status = soplex->solve();
-
-    soplex::Vector pv(primal_value.size(), &primal_value[0]);
-    soplex->getPrimal(pv);
-
-    soplex::Vector dv(dual_value.size(), &dual_value[0]);
-    soplex->getDual(dv);
 
     switch (status) {
@@ -239,5 +279,4 @@
     case soplex::SPxSolver::INFEASIBLE:
     case soplex::SPxSolver::UNBOUNDED:
-      solved = true;
       return SOLVED;
     default:
@@ -247,9 +286,19 @@
 
   LpSoplex::Value LpSoplex::_getPrimal(int i) const {
-    return primal_value[i];
+    if (_primal_values.empty()) {
+      _primal_values.resize(soplex->nCols());
+      soplex::Vector pv(_primal_values.size(), &_primal_values.front());
+      soplex->getPrimal(pv);
+    }
+    return _primal_values[i];
   }
 
   LpSoplex::Value LpSoplex::_getDual(int i) const {
-    return dual_value[i];
+    if (_dual_values.empty()) {
+      _dual_values.resize(soplex->nRows());
+      soplex::Vector dv(_dual_values.size(), &_dual_values.front());
+      soplex->getDual(dv);
+    }
+    return _dual_values[i];
   }
 
@@ -258,15 +307,64 @@
   }
 
-  bool LpSoplex::_isBasicCol(int i) const {
-    return soplex->getBasisColStatus(i) == soplex::SPxSolver::BASIC;
-  }
-
-  LpSoplex::SolutionStatus LpSoplex::_getPrimalStatus() const {
-    if (!solved) return UNDEFINED;
+  LpSoplex::VarStatus LpSoplex::_getColStatus(int i) const {
+    switch (soplex->getBasisColStatus(i)) {
+    case soplex::SPxSolver::BASIC:
+      return BASIC;
+    case soplex::SPxSolver::ON_UPPER:
+      return UPPER;
+    case soplex::SPxSolver::ON_LOWER:
+      return LOWER;
+    case soplex::SPxSolver::FIXED:
+      return FIXED;
+    case soplex::SPxSolver::ZERO:
+      return FREE;
+    default:
+      LEMON_ASSERT(false, "Wrong column status");
+      return VarStatus();
+    }
+  }
+
+  LpSoplex::VarStatus LpSoplex::_getRowStatus(int i) const {
+    switch (soplex->getBasisRowStatus(i)) {
+    case soplex::SPxSolver::BASIC:
+      return BASIC;
+    case soplex::SPxSolver::ON_UPPER:
+      return UPPER;
+    case soplex::SPxSolver::ON_LOWER:
+      return LOWER;
+    case soplex::SPxSolver::FIXED:
+      return FIXED;
+    case soplex::SPxSolver::ZERO:
+      return FREE;
+    default:
+      LEMON_ASSERT(false, "Wrong row status");
+      return VarStatus();
+    }
+  }
+
+  LpSoplex::Value LpSoplex::_getPrimalRay(int i) const {
+    if (_primal_ray.empty()) {
+      _primal_ray.resize(soplex->nCols());
+      soplex::Vector pv(_primal_ray.size(), &_primal_ray.front());
+      soplex->getDualfarkas(pv);
+    }
+    return _primal_ray[i];
+  }
+
+  LpSoplex::Value LpSoplex::_getDualRay(int i) const {
+    if (_dual_ray.empty()) {
+      _dual_ray.resize(soplex->nRows());
+      soplex::Vector dv(_dual_ray.size(), &_dual_ray.front());
+      soplex->getDualfarkas(dv);
+    }
+    return _dual_ray[i];
+  }
+
+  LpSoplex::ProblemType LpSoplex::_getPrimalType() const {
     switch (soplex->status()) {
     case soplex::SPxSolver::OPTIMAL:
       return OPTIMAL;
     case soplex::SPxSolver::UNBOUNDED:
-      return INFINITE;
+      return UNBOUNDED;
     case soplex::SPxSolver::INFEASIBLE:
       return INFEASIBLE;
@@ -276,10 +374,11 @@
   }
 
-  LpSoplex::SolutionStatus LpSoplex::_getDualStatus() const {
-    if (!solved) return UNDEFINED;
+  LpSoplex::ProblemType LpSoplex::_getDualType() const {
     switch (soplex->status()) {
     case soplex::SPxSolver::OPTIMAL:
       return OPTIMAL;
     case soplex::SPxSolver::UNBOUNDED:
+      return UNBOUNDED;
+    case soplex::SPxSolver::INFEASIBLE:
       return INFEASIBLE;
     default:
@@ -288,28 +387,36 @@
   }
 
-  LpSoplex::ProblemTypes LpSoplex::_getProblemType() const {
-    if (!solved) return UNKNOWN;
-    switch (soplex->status()) {
-    case soplex::SPxSolver::OPTIMAL:
-      return PRIMAL_DUAL_FEASIBLE;
-    case soplex::SPxSolver::UNBOUNDED:
-      return PRIMAL_FEASIBLE_DUAL_INFEASIBLE;
-    default:
-      return UNKNOWN;
-    }
-  }
-
-  void LpSoplex::_setMax() {
-    soplex->changeSense(soplex::SPxSolver::MAXIMIZE);
-    solved = false;
-  }
-  void LpSoplex::_setMin() {
-    soplex->changeSense(soplex::SPxSolver::MINIMIZE);
-    solved = false;
-  }
-  bool LpSoplex::_isMax() const {
-    return soplex->spxSense() == soplex::SPxSolver::MAXIMIZE;
-  }
-
+  void LpSoplex::_setSense(Sense sense) {
+    switch (sense) {
+    case MIN:
+      soplex->changeSense(soplex::SPxSolver::MINIMIZE);
+      break;
+    case MAX:
+      soplex->changeSense(soplex::SPxSolver::MAXIMIZE);
+    }
+  }
+
+  LpSoplex::Sense LpSoplex::_getSense() const {
+    switch (soplex->spxSense()) {
+    case soplex::SPxSolver::MAXIMIZE:
+      return MAX;
+    case soplex::SPxSolver::MINIMIZE:
+      return MIN;
+    default:
+      LEMON_ASSERT(false, "Wrong sense.");
+      return LpSoplex::Sense();
+    }
+  }
+
+  void LpSoplex::_clear() {
+    soplex->clear();
+    _col_names.clear();
+    _col_names_ref.clear();
+    _row_names.clear();
+    _row_names_ref.clear();
+    cols.clear();
+    rows.clear();
+    _clear_temporals();
+  }
 
 } //namespace lemon
Index: lemon/lp_soplex.h
===================================================================
--- lemon/lp_soplex.h	(revision 458)
+++ lemon/lp_soplex.h	(revision 459)
@@ -44,23 +44,27 @@
   /// Berlin (ZIB). You can find detailed information about it at the
   /// <tt>http://soplex.zib.de</tt> address.
-  class LpSoplex :virtual public LpSolverBase {
-  protected:
-
-    _lp_bits::RelocateIdHandler relocateIdHandler;
+  class LpSoplex : public LpSolver {
+  private:
 
     soplex::SoPlex* soplex;
-    bool solved;
 
-    std::vector<std::string> colNames;
-    std::map<std::string, int> invColNames;
+    std::vector<std::string> _col_names;
+    std::map<std::string, int> _col_names_ref;
 
-    std::vector<Value> primal_value;
-    std::vector<Value> dual_value;
+    std::vector<std::string> _row_names;
+    std::map<std::string, int> _row_names_ref;
 
+  private:
+
+    // these values cannot be retrieved element by element
+    mutable std::vector<Value> _primal_values;
+    mutable std::vector<Value> _dual_values;
+
+    mutable std::vector<Value> _primal_ray;
+    mutable std::vector<Value> _dual_ray;
+
+    void _clear_temporals();
 
   public:
-
-    typedef LpSolverBase Parent;
-
 
     /// \e
@@ -73,46 +77,73 @@
   protected:
 
-    virtual LpSolverBase* _newLp();
-    virtual LpSolverBase* _copyLp();
+    virtual LpSoplex* _newSolver() const;
+    virtual LpSoplex* _cloneSolver() const;
+
+    virtual const char* _solverName() const;
 
     virtual int _addCol();
     virtual int _addRow();
+
     virtual void _eraseCol(int i);
     virtual void _eraseRow(int i);
-    virtual void _getColName(int col, std::string & name) const;
-    virtual void _setColName(int col, const std::string & name);
+
+    virtual void _eraseColId(int i);
+    virtual void _eraseRowId(int i);
+
+    virtual void _getColName(int col, std::string& name) const;
+    virtual void _setColName(int col, const std::string& name);
     virtual int _colByName(const std::string& name) const;
-    virtual void _setRowCoeffs(int i, ConstRowIterator b, ConstRowIterator e);
-    virtual void _getRowCoeffs(int i, RowIterator b) const;
-    virtual void _setColCoeffs(int i, ConstColIterator b, ConstColIterator e);
-    virtual void _getColCoeffs(int i, ColIterator b) const;
+
+    virtual void _getRowName(int row, std::string& name) const;
+    virtual void _setRowName(int row, const std::string& name);
+    virtual int _rowByName(const std::string& name) const;
+
+    virtual void _setRowCoeffs(int i, ExprIterator b, ExprIterator e);
+    virtual void _getRowCoeffs(int i, InsertIterator b) const;
+
+    virtual void _setColCoeffs(int i, ExprIterator b, ExprIterator e);
+    virtual void _getColCoeffs(int i, InsertIterator b) const;
+
     virtual void _setCoeff(int row, int col, Value value);
     virtual Value _getCoeff(int row, int col) const;
+
     virtual void _setColLowerBound(int i, Value value);
     virtual Value _getColLowerBound(int i) const;
     virtual void _setColUpperBound(int i, Value value);
     virtual Value _getColUpperBound(int i) const;
-    virtual void _setRowBounds(int i, Value lower, Value upper);
-    virtual void _getRowBounds(int i, Value &lower, Value &upper) const;
+
+    virtual void _setRowLowerBound(int i, Value value);
+    virtual Value _getRowLowerBound(int i) const;
+    virtual void _setRowUpperBound(int i, Value value);
+    virtual Value _getRowUpperBound(int i) const;
+
+    virtual void _setObjCoeffs(ExprIterator b, ExprIterator e);
+    virtual void _getObjCoeffs(InsertIterator b) const;
+
     virtual void _setObjCoeff(int i, Value obj_coef);
     virtual Value _getObjCoeff(int i) const;
-    virtual void _clearObj();
+
+    virtual void _setSense(Sense sense);
+    virtual Sense _getSense() const;
 
     virtual SolveExitStatus _solve();
     virtual Value _getPrimal(int i) const;
     virtual Value _getDual(int i) const;
+
     virtual Value _getPrimalValue() const;
-    virtual bool _isBasicCol(int i) const;
 
-    virtual SolutionStatus _getPrimalStatus() const;
-    virtual SolutionStatus _getDualStatus() const;
-    virtual ProblemTypes _getProblemType() const;
+    virtual Value _getPrimalRay(int i) const;
+    virtual Value _getDualRay(int i) const;
 
+    virtual VarStatus _getColStatus(int i) const;
+    virtual VarStatus _getRowStatus(int i) const;
 
-    virtual void _setMax();
-    virtual void _setMin();
-    virtual bool _isMax() const;
+    virtual ProblemType _getPrimalType() const;
+    virtual ProblemType _getDualType() const;
+
+    virtual void _clear();
 
   };
+
 } //END OF NAMESPACE LEMON
 
Index: lemon/mip_cplex.cc
===================================================================
--- lemon/mip_cplex.cc	(revision 458)
+++ 	(revision )
@@ -1,141 +1,0 @@
-/* -*- mode: C++; indent-tabs-mode: nil; -*-
- *
- * This file is a part of LEMON, a generic C++ optimization library.
- *
- * Copyright (C) 2003-2008
- * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
- * (Egervary Research Group on Combinatorial Optimization, EGRES).
- *
- * Permission to use, modify and distribute this software is granted
- * provided that this copyright notice appears in all copies. For
- * precise terms see the accompanying LICENSE file.
- *
- * This software is provided "AS IS" with no warranty of any kind,
- * express or implied, and with no claim as to its suitability for any
- * purpose.
- *
- */
-
-///\file
-///\brief Implementation of the LEMON-CPLEX mip solver interface.
-
-#include <lemon/mip_cplex.h>
-
-extern "C" {
-#include <ilcplex/cplex.h>
-}
-
-namespace lemon {
-
-  MipCplex::MipCplex() {
-    //This is unnecessary: setting integrality constraints on
-    //variables will set this, too
-
-    ///\todo The constant CPXPROB_MIP is
-    ///called CPXPROB_MILP in later versions
-#if CPX_VERSION < 800
-    CPXchgprobtype( env,  lp, CPXPROB_MIP);
-#else
-    CPXchgprobtype( env,  lp, CPXPROB_MILP);
-#endif
-
-  }
-
-  void MipCplex::_colType(int i, MipCplex::ColTypes col_type){
-
-    // Note If a variable is to be changed to binary, a call to CPXchgbds
-    // should also be made to change the bounds to 0 and 1.
-
-    int indices[1];
-    indices[0]=i;
-    char ctype[1];
-    switch (col_type){
-      case INT:
-        ctype[0]=CPX_INTEGER;//'I'
-        break;
-      case REAL:
-        ctype[0]=CPX_CONTINUOUS        ;//'C'
-        break;
-    default:;
-        //FIXME problem
-    }
-    CPXchgctype (env, lp, 1, indices, ctype);
-  }
-
-  MipCplex::ColTypes MipCplex::_colType(int i) const {
-
-    char ctype[1];
-    CPXgetctype (env, lp, ctype, i, i);
-    switch (ctype[0]){
-
-    case CPX_INTEGER:
-      return INT;
-    case CPX_CONTINUOUS:
-      return REAL;
-    default:
-      return REAL;//Error!
-    }
-
-  }
-
-  LpCplex::SolveExitStatus MipCplex::_solve(){
-
-    status = CPXmipopt (env, lp);
-    if (status==0)
-      return SOLVED;
-    else
-      return UNSOLVED;
-
-  }
-
-
-  LpCplex::SolutionStatus MipCplex::_getMipStatus() const {
-
-    int stat = CPXgetstat(env, lp);
-
-    //Fortunately, MIP statuses did not change for cplex 8.0
-    switch (stat)
-    {
-      case CPXMIP_OPTIMAL:
-        // Optimal integer solution has been found.
-      case CPXMIP_OPTIMAL_TOL:
-        // Optimal soluton with the tolerance defined by epgap or epagap has
-        // been found.
-        return OPTIMAL;
-        //This also exists in later issues
-        //    case CPXMIP_UNBOUNDED:
-        //return INFINITE;
-      case CPXMIP_INFEASIBLE:
-        return INFEASIBLE;
-      default:
-        return UNDEFINED;
-    }
-    //Unboundedness not treated well: the following is from cplex 9.0 doc
-    // About Unboundedness
-
-    // The treatment of models that are unbounded involves a few
-    // subtleties. Specifically, a declaration of unboundedness means that
-    // ILOG CPLEX has determined that the model has an unbounded
-    // ray. Given any feasible solution x with objective z, a multiple of
-    // the unbounded ray can be added to x to give a feasible solution
-    // with objective z-1 (or z+1 for maximization models). Thus, if a
-    // feasible solution exists, then the optimal objective is
-    // unbounded. Note that ILOG CPLEX has not necessarily concluded that
-    // a feasible solution exists. Users can call the routine CPXsolninfo
-    // to determine whether ILOG CPLEX has also concluded that the model
-    // has a feasible solution.
-
-  }
-
-  MipCplex::Value MipCplex::_getPrimal(int i) const {
-    Value x;
-    CPXgetmipx(env, lp, &x, i, i);
-    return x;
-  }
-
-  MipCplex::Value MipCplex::_getPrimalValue() const {
-    Value objval;
-    CPXgetmipobjval(env, lp, &objval);
-    return objval;
-  }
-} //END OF NAMESPACE LEMON
Index: lemon/mip_cplex.h
===================================================================
--- lemon/mip_cplex.h	(revision 458)
+++ 	(revision )
@@ -1,61 +1,0 @@
-/* -*- mode: C++; indent-tabs-mode: nil; -*-
- *
- * This file is a part of LEMON, a generic C++ optimization library.
- *
- * Copyright (C) 2003-2008
- * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
- * (Egervary Research Group on Combinatorial Optimization, EGRES).
- *
- * Permission to use, modify and distribute this software is granted
- * provided that this copyright notice appears in all copies. For
- * precise terms see the accompanying LICENSE file.
- *
- * This software is provided "AS IS" with no warranty of any kind,
- * express or implied, and with no claim as to its suitability for any
- * purpose.
- *
- */
-
-#ifndef LEMON_MIP_CPLEX_H
-#define LEMON_MIP_CPLEX_H
-
-///\file
-///\brief Header of the LEMON-CPLEX mip solver interface.
-///\ingroup lp_group
-
-
-#include <lemon/lp_cplex.h>
-
-namespace lemon {
-
-  /// \brief Interface for the CPLEX MIP solver
-  ///
-  /// This class implements an interface for the CPLEX MIP solver.
-  ///\ingroup lp_group
-  class MipCplex : public MipSolverBase, public LpCplex{
-
-  public:
-
-    typedef MipSolverBase ParentMip;
-    typedef LpCplex ParentLp;
-
-    MipCplex();
-    //~MipCplex();
-
-
-
-
-  protected:
-
-    virtual ColTypes _colType(int col) const;
-    virtual void _colType(int col, ColTypes col_type);
-
-    virtual LpCplex::SolveExitStatus _solve();
-    virtual LpCplex::SolutionStatus _getMipStatus() const;
-    virtual ParentLp::Value _getPrimal(int i) const;
-    virtual ParentLp::Value _getPrimalValue() const;
-  };
-
-} //END OF NAMESPACE LEMON
-
-#endif // END OF LEMON_MIP_CPLEX_H
Index: lemon/mip_glpk.cc
===================================================================
--- lemon/mip_glpk.cc	(revision 458)
+++ 	(revision )
@@ -1,154 +1,0 @@
-/* -*- mode: C++; indent-tabs-mode: nil; -*-
- *
- * This file is a part of LEMON, a generic C++ optimization library.
- *
- * Copyright (C) 2003-2008
- * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
- * (Egervary Research Group on Combinatorial Optimization, EGRES).
- *
- * Permission to use, modify and distribute this software is granted
- * provided that this copyright notice appears in all copies. For
- * precise terms see the accompanying LICENSE file.
- *
- * This software is provided "AS IS" with no warranty of any kind,
- * express or implied, and with no claim as to its suitability for any
- * purpose.
- *
- */
-
-///\file
-///\brief Implementation of the LEMON-GLPK mip solver interface.
-
-#include <lemon/mip_glpk.h>
-
-extern "C" {
-#include <glpk.h>
-}
-
-#if GLP_MAJOR_VERSION > 4 || (GLP_MAJOR_VERSION == 4 && GLP_MINOR_VERSION > 15)
-#define LEMON_glp(func) (glp_##func)
-#define LEMON_lpx(func) (lpx_##func)
-
-#define LEMON_GLP(def) (GLP_##def)
-#define LEMON_LPX(def) (LPX_##def)
-
-#else
-
-#define LEMON_glp(func) (lpx_##func)
-#define LEMON_lpx(func) (lpx_##func)
-
-#define LEMON_GLP(def) (LPX_##def)
-#define LEMON_LPX(def) (LPX_##def)
-
-#endif
-
-namespace lemon {
-
-  MipGlpk::MipGlpk() {
-#if !(GLP_MAJOR_VERSION > 4 || \
-      (GLP_MAJOR_VERSION == 4 && GLP_MINOR_VERSION > 15))
-    LEMON_lpx(set_class)(lp,LEMON_GLP(MIP));
-#endif
-  }
-
-  void MipGlpk::_colType(int i, MipGlpk::ColTypes col_type){
-    switch (col_type){
-      case INT:
-        LEMON_glp(set_col_kind)(lp,i,LEMON_GLP(IV));
-        break;
-      case REAL:
-        LEMON_glp(set_col_kind)(lp,i,LEMON_GLP(CV));
-        break;
-    default:;
-        //FIXME problem
-    }
-  }
-
-  MipGlpk::ColTypes MipGlpk::_colType(int i) const {
-    switch (LEMON_glp(get_col_kind)(lp,i)){
-    case LEMON_GLP(IV):
-      return INT;//Or binary
-    case LEMON_GLP(CV):
-      return REAL;
-    default:
-      return REAL;//Error!
-    }
-
-  }
-
-  LpGlpk::SolveExitStatus MipGlpk::_solve() {
-    int result = LEMON_lpx(simplex)(lp);
-
-    // hack: mip does not contain integer variable
-#if GLP_MAJOR_VERSION == 4 && GLP_MINOR_VERSION == 16
-    int tmp = -1;
-    if (LEMON_glp(get_num_int(lp)) == 0) {
-      tmp = LEMON_lpx(add_cols)(lp, 1);
-      LEMON_glp(set_col_bnds)(lp, tmp, LEMON_GLP(FX), 0.0, 0.0);
-      LEMON_glp(set_col_kind)(lp, tmp, LEMON_GLP(IV));
-    }
-#endif
-
-    if (LEMON_lpx(get_status)(lp)==LEMON_LPX(OPT)) {
-      //Maybe we could try the routine lpx_intopt(lp), a revised
-      //version of lpx_integer
-
-      result = LEMON_lpx(integer)(lp);
-      switch (result){
-      case LEMON_LPX(E_OK):
-        solved = true;
-        break;
-      default:
-        solved = false;
-      }
-    } else {
-      solved = false;
-    }
-#if GLP_MAJOR_VERSION == 4 && GLP_MINOR_VERSION == 16
-    if (tmp != -1) {
-      int tmpa[2];
-      tmpa[1] = tmp;
-      LEMON_lpx(del_cols)(lp, 1, tmpa);
-    }
-#endif
-    return solved ? SOLVED : UNSOLVED;
-  }
-
-
-  LpGlpk::SolutionStatus MipGlpk::_getMipStatus() const {
-
-    if (LEMON_lpx(get_status)(lp)==LEMON_LPX(OPT)){
-      //Meg kell nezni: ha az LP is infinite, akkor ez is, ha az is
-      //infeasible, akkor ez is, de ez lehet maskepp is infeasible.
-      int stat= LEMON_lpx(mip_status)(lp);
-
-      switch (stat) {
-      case LEMON_LPX(I_UNDEF)://Undefined (no solve has been run yet)
-        return UNDEFINED;
-      case LEMON_LPX(I_NOFEAS)://There is no feasible integral solution
-        return INFEASIBLE;
-        //     case LEMON_LPX(UNBND)://Unbounded
-        //       return INFINITE;
-      case LEMON_LPX(I_FEAS)://Feasible
-        return FEASIBLE;
-      case LEMON_LPX(I_OPT)://Feasible
-        return OPTIMAL;
-      default:
-        return UNDEFINED; //to avoid gcc warning
-      //FIXME error
-      }
-    }
-    else
-      return UNDEFINED; //Maybe we could refine this: what does the LP
-                        //relaxation look like
-
-  }
-
-  MipGlpk::Value MipGlpk::_getPrimal(int i) const {
-    return LEMON_glp(mip_col_val)(lp,i);
-  }
-
-  MipGlpk::Value MipGlpk::_getPrimalValue() const {
-    return LEMON_glp(mip_obj_val)(lp);
-  }
-} //END OF NAMESPACE LEMON
Index: lemon/mip_glpk.h
===================================================================
--- lemon/mip_glpk.h	(revision 458)
+++ 	(revision )
@@ -1,59 +1,0 @@
-/* -*- mode: C++; indent-tabs-mode: nil; -*-
- *
- * This file is a part of LEMON, a generic C++ optimization library.
- *
- * Copyright (C) 2003-2008
- * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
- * (Egervary Research Group on Combinatorial Optimization, EGRES).
- *
- * Permission to use, modify and distribute this software is granted
- * provided that this copyright notice appears in all copies. For
- * precise terms see the accompanying LICENSE file.
- *
- * This software is provided "AS IS" with no warranty of any kind,
- * express or implied, and with no claim as to its suitability for any
- * purpose.
- *
- */
-
-#ifndef LEMON_MIP_GLPK_H
-#define LEMON_MIP_GLPK_H
-
-///\file
-///\brief Header of the LEMON-GLPK mip solver interface.
-///\ingroup lp_group
-
-
-#include <lemon/lp_glpk.h>
-
-namespace lemon {
-  /// \brief Interface for the GLPK MIP solver
-  ///
-  /// This class implements an interface for the GLPK MIP solver.
-  ///\ingroup lp_group
-  class MipGlpk : public MipSolverBase, public LpGlpk{
-
-  public:
-
-    typedef MipSolverBase ParentMip;
-    typedef LpGlpk ParentLp;
-
-    MipGlpk();
-    //~MipGlpk();
-
-
-
-  protected:
-
-    virtual ColTypes _colType(int col) const;
-    virtual void _colType(int col, ColTypes col_type);
-
-    virtual LpGlpk::SolveExitStatus _solve();
-    virtual LpGlpk::SolutionStatus _getMipStatus() const;
-    virtual ParentLp::Value _getPrimal(int i) const;
-    virtual ParentLp::Value _getPrimalValue() const;
-  };
-
-} //END OF NAMESPACE LEMON
-
-#endif // END OF LEMON_MIP_GLPK_H
