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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/* */
/* This file is part of the program and library */
/* SCIP --- Solving Constraint Integer Programs */
/* */
/* Copyright 2002-2022 Zuse Institute Berlin */
/* */
/* Licensed under the Apache License, Version 2.0 (the "License"); */
/* you may not use this file except in compliance with the License. */
/* You may obtain a copy of the License at */
/* */
/* http://www.apache.org/licenses/LICENSE-2.0 */
/* */
/* Unless required by applicable law or agreed to in writing, software */
/* distributed under the License is distributed on an "AS IS" BASIS, */
/* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. */
/* See the License for the specific language governing permissions and */
/* limitations under the License. */
/* */
/* You should have received a copy of the Apache-2.0 license */
/* along with SCIP; see the file LICENSE. If not visit scipopt.org. */
/* */
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/**@file presolve.h
* @ingroup PUBLICCOREAPI
* @brief methods commonly used for presolving
* @author Michael Winkler
*/
/*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
#ifndef __SCIP_PRESOLVE_H__
#define __SCIP_PRESOLVE_H__
#include "scip/def.h"
#include "scip/type_retcode.h"
#include "scip/type_scip.h"
#include "scip/type_var.h"
#ifdef __cplusplus
extern "C" {
#endif
/**@defgroup PublicSpecialPresolveMethods Special Methods
* @ingroup PublicPresolverMethods
* @brief methods commonly used for presolving
*
* @{
*/
/** try to reduce the necessary variable in a set of variables with corresponding bounds and boundtypes for which one
* must be fulfilled
*
* e.g. a set of logicor or bounddisjunctive constraint variables would be such a set
*
* consider the following set:
*
* x1 >= 1, x2 >= 3, x3 >= 1, x4 <= 0
*
* by (global) implication data (cliques, implications, and variable bounds) we have also the following implications
* given:
*
* x1 >= 1 => x3 >= 1
* x2 >= 2 => x3 >= 1
* x4 <= 0 => x1 >= 1
*
* Because of the last implication x4 is redundant, because x1 >= 1 would also be fulfilled in the variable set, so we
* can reduce the set by x4.
* Also, the both other implications and x3 >= 1 (in the given variable set) all imply exactly x3 >= 1, so we tighten
* the global lower bound of x3 to 1 and the set of variables gets redundant.
*/
SCIP_EXPORT
SCIP_RETCODE SCIPshrinkDisjunctiveVarSet(
SCIP* scip, /**< SCIP data structure */
SCIP_VAR** vars, /**< variables array for which at least one must be fulfilled in the
* following bounds and boundtypes */
SCIP_Real* bounds, /**< bounds array for which at least one must be fulfilled */
SCIP_Bool* boundtypes, /**< boundtypes array (TRUE == SCIP_BOUNDTYPE_UPPER, FALSE == SCIP_BOUNDTYPE_LOWER)
* for which at least one must be fulfilled */
SCIP_Bool* redundants, /**< array which be filled and then indicate if a variable in the set is redundant */
int nvars, /**< number of variables */
int* nredvars, /**< pointer to store how many variables can be removed */
int* nglobalred, /**< pointer to store number of global reductions on variable bounds found
* through this set of variables */
SCIP_Bool* setredundant, /**< pointer to store if we found a global reduction on a variable which was part
* of the given set of variables, this makes this disjunction redundant */
SCIP_Bool* glbinfeas, /**< pointer to store if global infeasibility was detected */
SCIP_Bool fullshortening /**< do we want to try the shortening procedure over the whole set (which might be expensive) */
);
/** @} */
#ifdef __cplusplus
}
#endif
#endif