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4    	/*         SCIP --- Solving Constraint Integer Programs                      */
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24   	
25   	/**@file   heur_gins.h
26   	 * @ingroup PRIMALHEURISTICS
27   	 * @brief  LNS heuristic that tries to delimit the search region to a neighborhood in the constraint graph
28   	 * @author Gregor Hendel
29   	 *
30   	 *
31   	 * Graph Induced Neighborhood Search (GINS) is a Large Neighborhood Search Heuristic that attempts to improve
32   	 * an incumbent solution by fixing a suitable percentage of integer variables to the incumbent and
33   	 * solving the resulting, smaller and presumably easier sub-MIP.
34   	 *
35   	 * Its search neighborhoods are based on distances in a bipartite graph \f$G\f$ with the variables and constraints as nodes and
36   	 * an edge between a variable and a constraint, if the variable is part of the constraint.
37   	 * Given an integer \f$k\f$, the \f$k\f$-neighborhood of a variable \f$v\f$ in \f$G\f$ is the set of variables, whose nodes
38   	 * are connected to \f$v\f$ by a path not longer than \f$2 \cdot k\f$. Intuitively, a judiciously chosen neighborhood size
39   	 * allows to consider a local portion of the overall problem.
40   	 *
41   	 * An initial variable selection is made by randomly sampling different neighborhoods across the whole main problem.
42   	 * The neighborhood that offers the largest potential for improvement is selected to become the local search neighborhood,
43   	 * while all variables outside the neighborhood are fixed to their incumbent solution values.
44   	 *
45   	 * GINS also supports a rolling horizon approach, during which several local neighborhoods are considered
46   	 * with increasing distance to the variable selected for the initial sub-problem. The rolling horizon approach ends
47   	 * if no improvement could be found or a sufficient part of the problem component variables has been part of
48   	 * at least one neighborhood.
49   	 */
50   	
51   	/*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
52   	
53   	#ifndef __SCIP_HEUR_GINS_H__
54   	#define __SCIP_HEUR_GINS_H__
55   	
56   	#include "scip/def.h"
57   	#include "scip/type_retcode.h"
58   	#include "scip/type_scip.h"
59   	
60   	#ifdef __cplusplus
61   	extern "C" {
62   	#endif
63   	
64   	/** creates the gins primal heuristic and includes it in SCIP
65   	 *
66   	 *  @ingroup PrimalHeuristicIncludes
67   	 */
68   	SCIP_EXPORT
69   	SCIP_RETCODE SCIPincludeHeurGins(
70   	   SCIP*                 scip                /**< SCIP data structure */
71   	   );
72   	
73   	#ifdef __cplusplus
74   	}
75   	#endif
76   	
77   	#endif
78