Solving Constraint Integer Programs

Detailed Description

LNS heuristic using a clique partition to restrict the search neighborhood.

clique primal heuristic

Stefan Heinz
Michael Winkler
Gerald Gamrath

More details about the heuristic can be found in
Structure-Based Primal Heuristics for Mixed Integer Programming
Gerald Gamrath, Timo Berthold, Stefan Heinz, and Michael Winkler
Optimization in the Real World, Volume 13 of the series Mathematics for Industry, pp 37-53
Preliminary version available as ZIB-Report 15-26.

Definition in file heur_clique.c.

#include "blockmemshell/memory.h"
#include "scip/cons_logicor.h"
#include "scip/heur_clique.h"
#include "scip/heur_locks.h"
#include "scip/pub_heur.h"
#include "scip/pub_implics.h"
#include "scip/pub_message.h"
#include "scip/pub_misc.h"
#include "scip/pub_misc_sort.h"
#include "scip/pub_var.h"
#include "scip/scip_branch.h"
#include "scip/scip_cons.h"
#include "scip/scip_copy.h"
#include "scip/scip_general.h"
#include "scip/scip_heur.h"
#include "scip/scip_lp.h"
#include "scip/scip_mem.h"
#include "scip/scip_message.h"
#include "scip/scip_numerics.h"
#include "scip/scip_param.h"
#include "scip/scip_prob.h"
#include "scip/scip_probing.h"
#include "scip/scip_sol.h"
#include "scip/scip_solve.h"
#include "scip/scip_solvingstats.h"
#include "scip/scip_timing.h"
#include "scip/scip_tree.h"
#include "scip/scip_var.h"
#include <string.h>

Go to the source code of this file.


#define HEUR_NAME   "clique"
#define HEUR_DESC   "LNS heuristic using a clique partition to restrict the search neighborhood"
#define HEUR_PRIORITY   5000
#define HEUR_FREQ   0
#define HEUR_FREQOFS   0
#define HEUR_MAXDEPTH   -1


static SCIP_DECL_SORTINDCOMP (compCliquesSize)
static int getCliqueUnfixedVars (SCIP_CLIQUE *clique)
static SCIP_RETCODE applyCliqueFixings (SCIP *scip, SCIP_HEURDATA *heurdata, SCIP_Bool enabledconflicts, SCIP_VAR **onefixvars, SCIP_Shortbool *onefixvals, int *nonefixvars, SCIP_Bool *cutoff)
static SCIP_DECL_HEURCOPY (heurCopyClique)
static SCIP_DECL_HEURFREE (heurFreeClique)
static SCIP_DECL_HEURINIT (heurInitClique)
static SCIP_DECL_HEUREXEC (heurExecClique)
SCIP_RETCODE SCIPincludeHeurClique (SCIP *scip)

Macro Definition Documentation


#define HEUR_NAME   "clique"

Definition at line 76 of file heur_clique.c.


#define HEUR_DESC   "LNS heuristic using a clique partition to restrict the search neighborhood"

Definition at line 77 of file heur_clique.c.



Definition at line 78 of file heur_clique.c.


#define HEUR_PRIORITY   5000

Definition at line 79 of file heur_clique.c.


#define HEUR_FREQ   0

Definition at line 80 of file heur_clique.c.


#define HEUR_FREQOFS   0

Definition at line 81 of file heur_clique.c.


#define HEUR_MAXDEPTH   -1

Definition at line 82 of file heur_clique.c.



Definition at line 83 of file heur_clique.c.



does the heuristic use a secondary SCIP instance?

Definition at line 84 of file heur_clique.c.



maximum number of nodes to regard in the subproblem

Definition at line 86 of file heur_clique.c.



minimum percentage of integer variables that have to be fixed

Definition at line 87 of file heur_clique.c.



minimum percentage of variables that have to be fixed within sub-SCIP (integer and continuous)

Definition at line 88 of file heur_clique.c.



factor by which clique heuristic should at least improve the incumbent

Definition at line 91 of file heur_clique.c.



minimum number of nodes to regard in the subproblem

Definition at line 94 of file heur_clique.c.



number of nodes added to the contingent of the total nodes

Definition at line 95 of file heur_clique.c.



subproblem nodes in relation to nodes of the original problem

Definition at line 96 of file heur_clique.c.



maximum number of propagation rounds during probing

Definition at line 97 of file heur_clique.c.



maximum number of backtracks during the fixing process

Definition at line 98 of file heur_clique.c.



should all active cuts from the cutpool of the original scip be copied to constraints of the subscip

Definition at line 99 of file heur_clique.c.



should more variables be fixed based on variable locks if the fixing rate was not reached?

Definition at line 102 of file heur_clique.c.

Function Documentation


static SCIP_DECL_SORTINDCOMP ( compCliquesSize  )

comparison method for sorting cliques by their size

Definition at line 139 of file heur_clique.c.

◆ getCliqueUnfixedVars()

static int getCliqueUnfixedVars ( SCIP_CLIQUE clique)

Definition at line 147 of file heur_clique.c.

Referenced by applyCliqueFixings().

◆ applyCliqueFixings()

static SCIP_RETCODE applyCliqueFixings ( SCIP scip,
SCIP_Bool  enabledconflicts,
SCIP_VAR **  onefixvars,
SCIP_Shortbool onefixvals,
int *  nonefixvars,
SCIP_Bool cutoff 

apply clique fixing using probing

sciporiginal SCIP data structure
heurdatastructure containing heurdata
enabledconflictswas conflict analysis enabled before the heuristic call?
onefixvarsarray to store all variables which are fixed to one in the cliques
onefixvalsarray to store the values of all variables fixed to one in the cliques
nonefixvarspointer to store the number of variables fixed to one
cutoffpointer to store whether the propagation stopped with infeasibility

Definition at line 174 of file heur_clique.c.

References FALSE, getCliqueUnfixedVars(), NULL, SCIP_Bool, SCIP_CALL, SCIP_CONFTYPE_PROPAGATION, SCIP_DECL_HEURCOPY(), SCIP_LONGINT_FORMAT, SCIP_MAXSTRLEN, SCIP_MAXTREEDEPTH, SCIP_OKAY, SCIP_Real, SCIPaddConflict(), SCIPallocBufferArray, SCIPallocClearBufferArray, SCIPbacktrackProbing(), SCIPcliqueGetNVars(), SCIPcliqueGetValues(), SCIPcliqueGetVars(), SCIPcreateConsLogicor(), SCIPdebugMsg, SCIPdebugPrintCons, SCIPfixVarProbing(), SCIPfreeBufferArray, SCIPgetCliques(), SCIPgetDepth(), SCIPgetFocusNode(), SCIPgetNBinVars(), SCIPgetNCliques(), SCIPgetNegatedVar(), SCIPgetNNodes(), SCIPgetProbingDepth(), SCIPinfinity(), SCIPisStopped(), SCIPnewProbingNode(), SCIPpropagateProbing(), SCIPsnprintf(), SCIPsort(), SCIPvarGetLbLocal(), SCIPvarGetName(), SCIPvarGetObj(), SCIPvarGetUbLocal(), and TRUE.


static SCIP_DECL_HEURCOPY ( heurCopyClique  )

copy method for primal heuristic plugins (called when SCIP copies plugins)

Definition at line 520 of file heur_clique.c.

Referenced by applyCliqueFixings().


static SCIP_DECL_HEURFREE ( heurFreeClique  )

destructor of primal heuristic to free user data (called when SCIP is exiting)

Definition at line 534 of file heur_clique.c.


static SCIP_DECL_HEURINIT ( heurInitClique  )

initialization method of primal heuristic (called after problem was transformed)

Definition at line 555 of file heur_clique.c.


static SCIP_DECL_HEUREXEC ( heurExecClique  )

execution method of primal heuristic

Definition at line 574 of file heur_clique.c.