/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*                                                                           */
/*                  This file is part of the program and library             */
/*         SCIP --- Solving Constraint Integer Programs                      */
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/*  Copyright 2002-2022 Zuse Institute Berlin                                */
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/*  Licensed under the Apache License, Version 2.0 (the "License");          */
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/*      http://www.apache.org/licenses/LICENSE-2.0                           */
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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/**@file   heur_actconsdiving.h
 * @ingroup PRIMALHEURISTICS
 * @brief  LP diving heuristic that chooses fixings w.r.t. the active constraints the variable appear in
 * @author Tobias Achterberg
 *
 * Diving heuristic: Iteratively fixes some fractional variable and resolves the LP-relaxation, thereby simulating a
 * depth-first-search in the tree. Active Constraint Diving chooses a variable based on the active LP rows (equations
 * are counted twice here).  The variable score is calculated as a convex combination of the number of constraints the
 * variable appears in, the sum of all positive coefficients and the absolute sum of all negative coefficients. The
 * chosen variable is then rounded to the closest integer. One-level backtracking is applied: If the LP gets infeasible,
 * the last fixings 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_ACTCONSDIVING_H__
#define __SCIP_HEUR_ACTCONSDIVING_H__

#include "scip/def.h"
#include "scip/type_retcode.h"
#include "scip/type_scip.h"

#ifdef __cplusplus
extern "C" {
#endif

/** creates the actconsdiving heuristic and includes it in SCIP
 *
 *  @ingroup PrimalHeuristicIncludes
 */
SCIP_EXPORT
SCIP_RETCODE SCIPincludeHeurActconsdiving(
   SCIP*                 scip                /**< SCIP data structure */
   );

#ifdef __cplusplus
}
#endif

#endif