Scippy

SCIP

Solving Constraint Integer Programs

heur_locks.h
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2 /* */
3 /* This file is part of the program and library */
4 /* SCIP --- Solving Constraint Integer Programs */
5 /* */
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23 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
24 
25 /**@file heur_locks.h
26  * @ingroup PRIMALHEURISTICS
27  * @brief locks primal heuristic
28  * @author Michael Winkler
29  * @author Gerald Gamrath
30  *
31  * The locks heuristic is a start heuristic that first tries to fix all binary variables, then solves the resulting LP
32  * and tries to round the solution and finally solves a sub-MIP on the remaining problem if the LP solution could not be
33  * rounded. The fixing works as follows: First, all variables are sorted by their total number of rounding locks (up-
34  * and down-locks summed up). Then, looking at the variable with the highest number of locks first, the variable is
35  * fixed to the bound where there are fewer locks (in case of ties, the bound which is better w.r.t. the objective
36  * function). This fix is propagated and the activities of all LP rows are updated. If any LP row becomes redundant
37  * w.r.t. the updated bounds, we adjust the rounding locks.
38  */
39 
40 /*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/
41 
42 #ifndef __SCIP_HEUR_LOCKS_H__
43 #define __SCIP_HEUR_LOCKS_H__
44 
45 #include "scip/def.h"
46 #include "scip/type_heur.h"
47 #include "scip/type_retcode.h"
48 #include "scip/type_scip.h"
49 
50 #ifdef __cplusplus
51 extern "C" {
52 #endif
53 
54 /** creates the locks primal heuristic and includes it in SCIP
55  *
56  * @ingroup PrimalHeuristicIncludes
57  */
58 SCIP_EXPORT
60  SCIP* scip /**< SCIP data structure */
61  );
62 
63 
64 /** apply fix-and-propagate scheme based on variable locks
65  *
66  * @note probing mode of SCIP needs to be enabled before
67  */
68 SCIP_EXPORT
70  SCIP* scip, /**< SCIP data structure */
71  SCIP_HEURDATA* heurdata, /**< primal heuristic data */
72  SCIP_Bool* cutoff, /**< pointer to store if a cutoff was detected */
73  SCIP_Bool* allrowsfulfilled /**< pointer to store if all rows became redundant */
74  );
75 
76 #ifdef __cplusplus
77 }
78 #endif
79 
80 #endif
SCIP_RETCODE SCIPapplyLockFixings(SCIP *scip, SCIP_HEURDATA *heurdata, SCIP_Bool *cutoff, SCIP_Bool *allrowsfulfilled)
Definition: heur_locks.c:196
enum SCIP_Retcode SCIP_RETCODE
Definition: type_retcode.h:63
struct SCIP_HeurData SCIP_HEURDATA
Definition: type_heur.h:76
type definitions for return codes for SCIP methods
type definitions for primal heuristics
type definitions for SCIP&#39;s main datastructure
#define SCIP_Bool
Definition: def.h:93
SCIP_RETCODE SCIPincludeHeurLocks(SCIP *scip)
Definition: heur_locks.c:1085
common defines and data types used in all packages of SCIP