heur_pscostdiving.h

Go to the documentation of this file.

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*                                                                           */
/*                  This file is part of the program and library             */
/*         SCIP --- Solving Constraint Integer Programs                      */
/*                                                                           */
/*  Copyright (c) 2002-2024 Zuse Institute Berlin (ZIB)                      */
/*                                                                           */
/*  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_pscostdiving.h
 * @ingroup PRIMALHEURISTICS
 * @brief  LP diving heuristic that chooses fixings w.r.t. the pseudo cost values
 * @author Tobias Achterberg
 *
 * Diving heuristic: Iteratively fixes some fractional variable and resolves the LP-relaxation, thereby simulating a
 * depth-first-search in the tree. Pseudocost Diving chooses the variable with the smallest ratio of estimated objective
 * increase if rounding to either direction. If the variable is significantly different from its root LP vlaue, it will
 * be rounded into the direction it developed (see @ref heur_linesearchdiving.h), if it is close to an integral point,
 * it will be rounded to that one, otherwise it will be rounded into the direction of lower pseudocosts. One-level
 * backtracking is applied: If the LP gets infeasible, the last fixing is undone, and the opposite fixing is tried. If
 * this is infeasible, too, the procedure aborts.
 */
 
/*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
 
#ifndef __SCIP_HEUR_PSCOSTDIVING_H__
#define __SCIP_HEUR_PSCOSTDIVING_H__
 
#include "scip/def.h"
#include "scip/type_retcode.h"
#include "scip/type_scip.h"
 
#ifdef __cplusplus
extern "C" {
#endif
 
/** creates the pscostdiving heuristic and includes it in SCIP
 *
 *  @ingroup PrimalHeuristicIncludes
 */
SCIP_EXPORT
SCIP_RETCODE SCIPincludeHeurPscostdiving(
   SCIP*                 scip                /**< SCIP data structure */
   );
 
#ifdef __cplusplus
}
#endif
 
#endif