CoinPresolveForcing.hpp

/* $Id$ */
// Copyright (C) 2002, International Business Machines
// Corporation and others.  All Rights Reserved.
// This code is licensed under the terms of the Eclipse Public License (EPL).

#ifndef CoinPresolveForcing_H
#define CoinPresolveForcing_H

#include "CoinPresolveMatrix.hpp"

/*!
  \file
*/

#define IMPLIED_BOUND 7

/*! \class forcing_constraint_action
    \brief Detect and process forcing constraints and useless constraints

  A constraint is useless if the bounds on the variables prevent the constraint
  from ever being violated.

  A constraint is a forcing constraint if the bounds on the constraint force
  the value of an involved variable to one of its bounds. A constraint can
  force more than one variable.
*/
class forcing_constraint_action : public CoinPresolveAction {
  forcing_constraint_action();
  forcing_constraint_action(const forcing_constraint_action &rhs);
  forcing_constraint_action &operator=(const forcing_constraint_action &rhs);

public:
  struct action {
    const int *rowcols;
    const double *bounds;
    int row;
    int nlo;
    int nup;
  };

private:
  const int nactions_;
  // actions_ is owned by the class and must be deleted at destruction
  const action *const actions_;

public:
  forcing_constraint_action(int nactions,
    const action *actions,
    const CoinPresolveAction *next)
    : CoinPresolveAction(next)
    , nactions_(nactions)
    , actions_(actions)
  {
  }

  const char *name() const;

  static const CoinPresolveAction *presolve(CoinPresolveMatrix *prob,
    const CoinPresolveAction *next);

  void postsolve(CoinPostsolveMatrix *prob) const;

  virtual ~forcing_constraint_action();
};

#endif

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