diff -r 1cfb25ef14d2 -r c91e765266d7 src/work/marci/lp/expression.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/work/marci/lp/expression.h	Wed Jan 26 15:54:06 2005 +0000
@@ -0,0 +1,91 @@
+// -*- c++ -*-
+#ifndef LEMON_EXPRESSION_H
+#define LEMON_EXPRESSION_H
+
+#include <iostream>
+#include <map>
+
+namespace lemon {
+
+  /*! \brief Linear expression
+
+    \c Expr<_Col,_Value> implements a class of linear expressions with the 
+    operations of addition and multiplication with scalar. 
+
+    \author Marton Makai
+   */
+  template <typename _Col, typename _Value>
+  class Expr;
+
+  template <typename _Col, typename _Value>
+  class Expr {
+  protected:
+    typedef 
+    typename std::map<_Col, _Value> Data; 
+    Data data;
+  public:
+    Expr() { }
+    Expr(_Col _col) { 
+      data.insert(std::make_pair(_col, 1));
+    }
+    Expr& operator*=(_Value _value) {
+      for (typename Data::iterator i=data.begin(); 
+	   i!=data.end(); ++i) {
+	(*i).second *= _value;
+      }
+      return *this;
+    }
+    Expr& operator+=(const Expr<_Col, _Value>& expr) {
+      for (typename Data::const_iterator j=expr.data.begin(); 
+	   j!=expr.data.end(); ++j) {
+	typename Data::iterator i=data.find((*j).first);
+	if (i==data.end()) {
+	  data.insert(std::make_pair((*j).first, (*j).second));
+	} else {
+	  (*i).second+=(*j).second;
+	}
+      }
+      return *this;
+    }
+    template <typename _C, typename _V> 
+    friend std::ostream& operator<<(std::ostream& os, 
+				    const Expr<_C, _V>& expr);
+  };
+
+  template <typename _Col, typename _Value>
+  Expr<_Col, _Value> operator*(_Value _value, _Col _col) {
+    Expr<_Col, _Value> tmp(_col);
+    tmp*=_value;
+    return tmp;
+  }
+
+  template <typename _Col, typename _Value>
+  Expr<_Col, _Value> operator*(_Value _value, 
+			       const Expr<_Col, _Value>& expr) {
+    Expr<_Col, _Value> tmp(expr);
+    tmp*=_value;
+    return tmp;
+  }
+
+  template <typename _Col, typename _Value>
+  Expr<_Col, _Value> operator+(const Expr<_Col, _Value>& expr1, 
+			       const Expr<_Col, _Value>& expr2) {
+    Expr<_Col, _Value> tmp(expr1);
+    tmp+=expr2;
+    return tmp;
+  }
+
+  template <typename _Col, typename _Value>
+  std::ostream& operator<<(std::ostream& os, 
+			   const Expr<_Col, _Value>& expr) {
+    for (typename Expr<_Col, _Value>::Data::const_iterator i=
+	   expr.data.begin(); 
+	 i!=expr.data.end(); ++i) {
+      os << (*i).second << "*" << (*i).first << " ";
+    }
+    return os;
+  }
+  
+} //namespace lemon
+
+#endif //LEMON_EXPRESSION_H