lemon/lp_skeleton.h
author Peter Kovacs <kpeter@inf.elte.hu>
Sat, 20 Feb 2010 18:39:03 +0100
changeset 839 f3bc4e9b5f3a
parent 576 745e182d0139
child 877 141f9c0db4a3
permissions -rw-r--r--
New heuristics for MCF algorithms (#340)
and some implementation improvements.

- A useful heuristic is added to NetworkSimplex to make the
initial pivots faster.
- A powerful global update heuristic is added to CostScaling
and the implementation is reworked with various improvements.
- Better relabeling in CostScaling to improve numerical stability
and make the code faster.
- A small improvement is made in CapacityScaling for better
delta computation.
- Add notes to the classes about the usage of vector<char> instead
of vector<bool> for efficiency reasons.
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/* -*- mode: C++; indent-tabs-mode: nil; -*-
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 *
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 * This file is a part of LEMON, a generic C++ optimization library.
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 *
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 * Copyright (C) 2003-2008
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 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
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 * (Egervary Research Group on Combinatorial Optimization, EGRES).
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 *
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 * Permission to use, modify and distribute this software is granted
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 * provided that this copyright notice appears in all copies. For
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 * precise terms see the accompanying LICENSE file.
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 *
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 * This software is provided "AS IS" with no warranty of any kind,
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 * express or implied, and with no claim as to its suitability for any
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 * purpose.
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 *
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 */
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#ifndef LEMON_LP_SKELETON_H
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#define LEMON_LP_SKELETON_H
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#include <lemon/lp_base.h>
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///\file
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///\brief Skeleton file to implement LP/MIP solver interfaces
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///  
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///The classes in this file do nothing, but they can serve as skeletons when
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///implementing an interface to new solvers.
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namespace lemon {
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  ///A skeleton class to implement LP/MIP solver base interface
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  ///This class does nothing, but it can serve as a skeleton when
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  ///implementing an interface to new solvers.
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  class SkeletonSolverBase : public virtual LpBase {
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    int col_num,row_num;
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  protected:
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    SkeletonSolverBase()
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      : col_num(-1), row_num(-1) {}
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    /// \e
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    virtual int _addCol();
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    /// \e
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    virtual int _addRow();
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    /// \e
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    virtual int _addRow(Value l, ExprIterator b, ExprIterator e, Value u);
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    /// \e
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    virtual void _eraseCol(int i);
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    /// \e
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    virtual void _eraseRow(int i);
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    /// \e
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    virtual void _getColName(int col, std::string& name) const;
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    /// \e
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    virtual void _setColName(int col, const std::string& name);
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    /// \e
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    virtual int _colByName(const std::string& name) const;
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    /// \e
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    virtual void _getRowName(int row, std::string& name) const;
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    /// \e
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    virtual void _setRowName(int row, const std::string& name);
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    /// \e
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    virtual int _rowByName(const std::string& name) const;
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    /// \e
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    virtual void _setRowCoeffs(int i, ExprIterator b, ExprIterator e);
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    /// \e
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    virtual void _getRowCoeffs(int i, InsertIterator b) const;
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    /// \e
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    virtual void _setColCoeffs(int i, ExprIterator b, ExprIterator e);
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    /// \e
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    virtual void _getColCoeffs(int i, InsertIterator b) const;
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    /// Set one element of the coefficient matrix
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    virtual void _setCoeff(int row, int col, Value value);
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    /// Get one element of the coefficient matrix
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    virtual Value _getCoeff(int row, int col) const;
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    /// The lower bound of a variable (column) have to be given by an
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    /// extended number of type Value, i.e. a finite number of type
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    /// Value or -\ref INF.
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    virtual void _setColLowerBound(int i, Value value);
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    /// \e
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    /// The lower bound of a variable (column) is an
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    /// extended number of type Value, i.e. a finite number of type
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    /// Value or -\ref INF.
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    virtual Value _getColLowerBound(int i) const;
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    /// The upper bound of a variable (column) have to be given by an
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    /// extended number of type Value, i.e. a finite number of type
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    /// Value or \ref INF.
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    virtual void _setColUpperBound(int i, Value value);
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    /// \e
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    /// The upper bound of a variable (column) is an
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    /// extended number of type Value, i.e. a finite number of type
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    /// Value or \ref INF.
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    virtual Value _getColUpperBound(int i) const;
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    /// The lower bound of a constraint (row) have to be given by an
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    /// extended number of type Value, i.e. a finite number of type
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    /// Value or -\ref INF.
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    virtual void _setRowLowerBound(int i, Value value);
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    /// \e
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    /// The lower bound of a constraint (row) is an
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    /// extended number of type Value, i.e. a finite number of type
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    /// Value or -\ref INF.
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    virtual Value _getRowLowerBound(int i) const;
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    /// The upper bound of a constraint (row) have to be given by an
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    /// extended number of type Value, i.e. a finite number of type
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    /// Value or \ref INF.
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    virtual void _setRowUpperBound(int i, Value value);
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    /// \e
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    /// The upper bound of a constraint (row) is an
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    /// extended number of type Value, i.e. a finite number of type
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    /// Value or \ref INF.
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    virtual Value _getRowUpperBound(int i) const;
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    /// \e
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    virtual void _setObjCoeffs(ExprIterator b, ExprIterator e);
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    /// \e
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    virtual void _getObjCoeffs(InsertIterator b) const;
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    /// \e
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    virtual void _setObjCoeff(int i, Value obj_coef);
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    /// \e
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    virtual Value _getObjCoeff(int i) const;
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    ///\e
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    virtual void _setSense(Sense);
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    ///\e
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    virtual Sense _getSense() const;
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    ///\e
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    virtual void _clear();
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    ///\e
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    virtual void _messageLevel(MessageLevel);
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  };
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  /// \brief Skeleton class for an LP solver interface
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  ///
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  ///This class does nothing, but it can serve as a skeleton when
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  ///implementing an interface to new solvers.
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  ///\ingroup lp_group
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  class LpSkeleton : public LpSolver, public SkeletonSolverBase {
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  public:
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    ///\e
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    LpSkeleton() : LpSolver(), SkeletonSolverBase() {}
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    ///\e
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    virtual LpSkeleton* newSolver() const;
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    ///\e
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    virtual LpSkeleton* cloneSolver() const;
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  protected:
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    ///\e
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    virtual SolveExitStatus _solve();
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    ///\e
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    virtual Value _getPrimal(int i) const;
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    ///\e
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    virtual Value _getDual(int i) const;
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    ///\e
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    virtual Value _getPrimalValue() const;
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    ///\e
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    virtual Value _getPrimalRay(int i) const;
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    ///\e
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    virtual Value _getDualRay(int i) const;
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    ///\e
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    virtual ProblemType _getPrimalType() const;
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    ///\e
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    virtual ProblemType _getDualType() const;
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    ///\e
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    virtual VarStatus _getColStatus(int i) const;
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    ///\e
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    virtual VarStatus _getRowStatus(int i) const;
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    ///\e
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    virtual const char* _solverName() const;
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  };
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  /// \brief Skeleton class for a MIP solver interface
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  ///
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  ///This class does nothing, but it can serve as a skeleton when
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  ///implementing an interface to new solvers.
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  ///\ingroup lp_group
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  class MipSkeleton : public MipSolver, public SkeletonSolverBase {
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  public:
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    ///\e
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    MipSkeleton() : MipSolver(), SkeletonSolverBase() {}
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    ///\e
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    virtual MipSkeleton* newSolver() const;
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    ///\e
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    virtual MipSkeleton* cloneSolver() const;
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  protected:
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    ///\e
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    virtual SolveExitStatus _solve();
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    ///\e
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    virtual Value _getSol(int i) const;
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    ///\e
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    virtual Value _getSolValue() const;
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    ///\e
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    virtual ProblemType _getType() const;
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    ///\e
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    virtual const char* _solverName() const;
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  };
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} //namespace lemon
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#endif