File: CbcBranchToFixLots.hpp

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// $Id: CbcBranchToFixLots.hpp 1899 2013-04-09 18:12:08Z stefan $
// Copyright (C) 2004, International Business Machines
// Corporation and others.  All Rights Reserved.
// This code is licensed under the terms of the Eclipse Public License (EPL).

// Edwin 11/13/2009-- carved out of CbcBranchCut

#ifndef CbcBranchToFixLots_H
#define CbcBranchToFixLots_H

#include "CbcBranchCut.hpp"
#include "CbcBranchBase.hpp"
#include "OsiRowCut.hpp"
#include "CoinPackedMatrix.hpp"

/** Define a branch class that branches so that one way variables are fixed
    while the other way cuts off that solution.
    a) On reduced cost
    b) When enough ==1 or <=1 rows have been satisfied (not fixed - satisfied)
*/


class CbcBranchToFixLots : public CbcBranchCut {

public:

    // Default Constructor
    CbcBranchToFixLots ();

    /** Useful constructor - passed reduced cost tolerance and fraction we would like fixed.
        Also depth level to do at.
        Also passed number of 1 rows which when clean triggers fix
        Always does if all 1 rows cleaned up and number>0 or if fraction columns reached
        Also whether to create branch if can't reach fraction.
    */
    CbcBranchToFixLots (CbcModel * model, double djTolerance,
                        double fractionFixed, int depth,
                        int numberClean = 0,
                        const char * mark = NULL,
                        bool alwaysCreate = false);

    // Copy constructor
    CbcBranchToFixLots ( const CbcBranchToFixLots &);

    /// Clone
    virtual CbcObject * clone() const;

    // Assignment operator
    CbcBranchToFixLots & operator=( const CbcBranchToFixLots& rhs);

    // Destructor
    ~CbcBranchToFixLots ();

    /** Does a lot of the work,
        Returns 0 if no good, 1 if dj, 2 if clean, 3 if both
	FIXME: should use enum or equivalent to make these numbers clearer.
    */
    int shallWe() const;

    /// Infeasibility for an integer variable - large is 0.5, but also can be infinity when known infeasible.
    virtual double infeasibility(const OsiBranchingInformation * info,
                                 int &preferredWay) const;
    /** \brief Return true if object can take part in normal heuristics
    */
    virtual bool canDoHeuristics() const {
        return true;
    }

    /// Creates a branching object
    virtual CbcBranchingObject * createCbcBranch(OsiSolverInterface * solver, const OsiBranchingInformation * info, int way) ;
    /// Redoes data when sequence numbers change
    virtual void redoSequenceEtc(CbcModel * model, int numberColumns, const int * originalColumns);


protected:
    /// data

    /// Reduced cost tolerance i.e. dj has to be >= this before fixed
    double djTolerance_;
    /// We only need to make sure this fraction fixed
    double fractionFixed_;
    /// Never fix ones marked here
    char * mark_;
    /// Matrix by row
    CoinPackedMatrix matrixByRow_;
    /// Do if depth multiple of this
    int depth_;
    /// number of ==1 rows which need to be clean
    int numberClean_;
    /// If true then always create branch
    bool alwaysCreate_;
};
#endif