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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 heur_locks.h
* @ingroup PRIMALHEURISTICS
* @brief locks primal heuristic
* @author Michael Winkler
* @author Gerald Gamrath
*
* The locks heuristic is a start heuristic that first tries to fix all binary variables, then solves the resulting LP
* and tries to round the solution and finally solves a sub-MIP on the remaining problem if the LP solution could not be
* rounded. The fixing works as follows: First, all variables are sorted by their total number of rounding locks (up-
* and down-locks summed up). Then, looking at the variable with the highest number of locks first, the variable is
* fixed to the bound where there are fewer locks (in case of ties, the bound which is better w.r.t. the objective
* function). This fix is propagated and the activities of all LP rows are updated. If any LP row becomes redundant
* w.r.t. the updated bounds, we adjust the rounding locks.
*/
/*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
#ifndef __SCIP_HEUR_LOCKS_H__
#define __SCIP_HEUR_LOCKS_H__
#include "scip/def.h"
#include "scip/type_heur.h"
#include "scip/type_retcode.h"
#include "scip/type_scip.h"
#ifdef __cplusplus
extern "C" {
#endif
/** creates the locks primal heuristic and includes it in SCIP
*
* @ingroup PrimalHeuristicIncludes
*/
SCIP_EXPORT
SCIP_RETCODE SCIPincludeHeurLocks(
SCIP* scip /**< SCIP data structure */
);
/** apply fix-and-propagate scheme based on variable locks
*
* @note probing mode of SCIP needs to be enabled before
*/
SCIP_EXPORT
SCIP_RETCODE SCIPapplyLockFixings(
SCIP* scip, /**< SCIP data structure */
SCIP_HEURDATA* heurdata, /**< primal heuristic data */
SCIP_Bool* cutoff, /**< pointer to store if a cutoff was detected */
SCIP_Bool* allrowsfulfilled /**< pointer to store if all rows became redundant */
);
#ifdef __cplusplus
}
#endif
#endif