Scippy

SCIP

Solving Constraint Integer Programs

heur_gins.h
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1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
2 /* */
3 /* This file is part of the program and library */
4 /* SCIP --- Solving Constraint Integer Programs */
5 /* */
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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
70  SCIP* scip /**< SCIP data structure */
71  );
72 
73 #ifdef __cplusplus
74 }
75 #endif
76 
77 #endif
SCIP_RETCODE SCIPincludeHeurGins(SCIP *scip)
Definition: heur_gins.c:2616
enum SCIP_Retcode SCIP_RETCODE
Definition: type_retcode.h:63
type definitions for return codes for SCIP methods
type definitions for SCIP&#39;s main datastructure
common defines and data types used in all packages of SCIP