Scippy

    SCIP

    Solving Constraint Integer Programs

    presol_implics.h
    Go to the documentation of this file.
    1/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
    2/* */
    3/* This file is part of the program and library */
    4/* SCIP --- Solving Constraint Integer Programs */
    5/* */
    6/* Copyright (c) 2002-2025 Zuse Institute Berlin (ZIB) */
    7/* */
    8/* Licensed under the Apache License, Version 2.0 (the "License"); */
    9/* you may not use this file except in compliance with the License. */
    10/* You may obtain a copy of the License at */
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    12/* http://www.apache.org/licenses/LICENSE-2.0 */
    13/* */
    14/* Unless required by applicable law or agreed to in writing, software */
    15/* distributed under the License is distributed on an "AS IS" BASIS, */
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    17/* See the License for the specific language governing permissions and */
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    20/* You should have received a copy of the Apache-2.0 license */
    21/* along with SCIP; see the file LICENSE. If not visit scipopt.org. */
    22/* */
    23/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
    24
    25/**@file presol_implics.h
    26 * @ingroup PRESOLVERS
    27 * @brief implication graph presolver which checks for aggregations
    28 * @author Tobias Achterberg
    29 *
    30 * This presolver looks for variable implications in \f$x == 0\f$ and \f$x == 1\f$ with the same implied variable.
    31 * There are four possible cases:
    32 * \f[
    33 * x = 0 \Rightarrow y = lb,\; \mathrm{and}\; x = 1 \Rightarrow y = lb:\; \mathrm{fix}\; y\; \mathrm{to}\; lb
    34 * \f]
    35 * \f[
    36 * x = 0 \Rightarrow y = lb,\; \mathrm{and}\; x = 1 \Rightarrow y = ub:\; \mathrm{aggregate}\; y == lb + (ub-lb)x
    37 * \f]
    38 * \f[
    39 * x = 0 \Rightarrow y = ub,\; \mathrm{and}\; x = 1 \Rightarrow y = lb:\; \mathrm{aggregate}\; y == ub - (ub-lb)x
    40 * \f]
    41 * \f[
    42 * x = 0 \Rightarrow y = ub,\; \mathrm{and}\; x = 1 \Rightarrow y = ub:\; \mathrm{fix}\; y\; \mathrm{to}\; ub
    43 * \f]
    44 */
    45
    46/*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
    47
    48#ifndef __SCIP_PRESOL_IMPLICS_H__
    49#define __SCIP_PRESOL_IMPLICS_H__
    50
    51#include "scip/def.h"
    52#include "scip/type_retcode.h"
    53#include "scip/type_scip.h"
    54
    55#ifdef __cplusplus
    56extern "C" {
    57#endif
    58
    59/** creates the implics presolver and includes it in SCIP
    60 *
    61 * @ingroup PresolverIncludes
    62 */
    63SCIP_EXPORT
    64SCIP_RETCODE SCIPincludePresolImplics(
    65 SCIP* scip /**< SCIP data structure */
    66 );
    67
    68#ifdef __cplusplus
    69}
    70#endif
    71
    72#endif
    def.h
    common defines and data types used in all packages of SCIP
    SCIPincludePresolImplics
    SCIP_RETCODE SCIPincludePresolImplics(SCIP *scip)
    Definition: presol_implics.c:359
    type_retcode.h
    type definitions for return codes for SCIP methods
    SCIP_RETCODE
    enum SCIP_Retcode SCIP_RETCODE
    Definition: type_retcode.h:63
    type_scip.h
    type definitions for SCIP's main datastructure