Scippy

SCIP

Solving Constraint Integer Programs

Macros | Functions
heur_clique.c File Reference

Detailed Description

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

clique primal heuristic

Author
Stefan Heinz
Michael Winkler

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 <assert.h>
#include <string.h>
#include "scip/scip.h"
#include "scip/heur_clique.h"
#include "scip/cons_logicor.h"
#include "scip/pub_misc.h"

Go to the source code of this file.

Macros

#define HEUR_NAME   "clique"
 
#define HEUR_DESC   "LNS heuristic using a clique partition to restrict the search neighborhood"
 
#define HEUR_DISPCHAR   'Q'
 
#define HEUR_PRIORITY   -1000500
 
#define HEUR_FREQ   -1
 
#define HEUR_FREQOFS   0
 
#define HEUR_MAXDEPTH   -1
 
#define HEUR_TIMING   SCIP_HEURTIMING_BEFORENODE
 
#define HEUR_USESSUBSCIP   TRUE
 
#define DEFAULT_MAXNODES   5000LL
 
#define DEFAULT_MINFIXINGRATE   0.25
 
#define DEFAULT_MINIMPROVE   0.01
 
#define DEFAULT_MINNODES   500LL
 
#define DEFAULT_NODESOFS   500LL
 
#define DEFAULT_NODESQUOT   0.1
 
#define DEFAULT_MAXPROPROUNDS   2
 
#define DEFAULT_RANDSEED   61
 
#define DEFAULT_MULTIPLIER   1.1
 
#define DEFAULT_COPYCUTS   TRUE
 

Functions

static SCIP_DECL_SORTPTRCOMP (varObjSort)
 
static SCIP_RETCODE stableSortBinvars (SCIP *scip, SCIP_VAR **binvars, int nbinvars, int *cliquepartition, int ncliques)
 
static SCIP_RETCODE applyCliqueFixings (SCIP *scip, SCIP_HEURDATA *heurdata, SCIP_VAR **binvars, int nbinvars, int *cliquepartition, int ncliques, SCIP_VAR **onefixvars, int *nonefixvars, SCIP_SOL *sol, int *probingdepthofonefix, SCIP_Bool *cutoff, SCIP_RESULT *result)
 
static SCIP_RETCODE createNewSol (SCIP *scip, SCIP *subscip, SCIP_VAR **subvars, SCIP_SOL *newsol, SCIP_SOL *subsol, SCIP_Bool *success)
 
static SCIP_DECL_HEURCOPY (heurCopyClique)
 
static SCIP_DECL_HEURFREE (heurFreeClique)
 
static SCIP_DECL_HEURINIT (heurInitClique)
 
static SCIP_DECL_HEUREXIT (heurExitClique)
 
static SCIP_DECL_HEUREXEC (heurExecClique)
 
SCIP_RETCODE SCIPincludeHeurClique (SCIP *scip)
 

Macro Definition Documentation

◆ HEUR_NAME

#define HEUR_NAME   "clique"

Definition at line 43 of file heur_clique.c.

Referenced by createNewSol().

◆ HEUR_DESC

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

Definition at line 44 of file heur_clique.c.

◆ HEUR_DISPCHAR

#define HEUR_DISPCHAR   'Q'

Definition at line 45 of file heur_clique.c.

◆ HEUR_PRIORITY

#define HEUR_PRIORITY   -1000500

Definition at line 46 of file heur_clique.c.

◆ HEUR_FREQ

#define HEUR_FREQ   -1

Definition at line 47 of file heur_clique.c.

◆ HEUR_FREQOFS

#define HEUR_FREQOFS   0

Definition at line 48 of file heur_clique.c.

◆ HEUR_MAXDEPTH

#define HEUR_MAXDEPTH   -1

Definition at line 49 of file heur_clique.c.

◆ HEUR_TIMING

#define HEUR_TIMING   SCIP_HEURTIMING_BEFORENODE

Definition at line 50 of file heur_clique.c.

◆ HEUR_USESSUBSCIP

#define HEUR_USESSUBSCIP   TRUE

does the heuristic use a secondary SCIP instance?

Definition at line 51 of file heur_clique.c.

◆ DEFAULT_MAXNODES

#define DEFAULT_MAXNODES   5000LL

maximum number of nodes to regard in the subproblem

Definition at line 53 of file heur_clique.c.

◆ DEFAULT_MINFIXINGRATE

#define DEFAULT_MINFIXINGRATE   0.25

minimum percentage of variables that have to be fixed

Definition at line 54 of file heur_clique.c.

◆ DEFAULT_MINIMPROVE

#define DEFAULT_MINIMPROVE   0.01

factor by which clique heuristic should at least improve the incumbent

Definition at line 55 of file heur_clique.c.

◆ DEFAULT_MINNODES

#define DEFAULT_MINNODES   500LL

minimum number of nodes to regard in the subproblem

Definition at line 60 of file heur_clique.c.

◆ DEFAULT_NODESOFS

#define DEFAULT_NODESOFS   500LL

number of nodes added to the contingent of the total nodes

Definition at line 61 of file heur_clique.c.

◆ DEFAULT_NODESQUOT

#define DEFAULT_NODESQUOT   0.1

subproblem nodes in relation to nodes of the original problem

Definition at line 62 of file heur_clique.c.

◆ DEFAULT_MAXPROPROUNDS

#define DEFAULT_MAXPROPROUNDS   2

maximum number of propagation rounds during probing

Definition at line 63 of file heur_clique.c.

◆ DEFAULT_RANDSEED

#define DEFAULT_RANDSEED   61

random seed value to initialize the random permutation value for variables

Definition at line 64 of file heur_clique.c.

◆ DEFAULT_MULTIPLIER

#define DEFAULT_MULTIPLIER   1.1

value to increase node number to determine the next run

Definition at line 69 of file heur_clique.c.

◆ DEFAULT_COPYCUTS

#define DEFAULT_COPYCUTS   TRUE

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

Definition at line 70 of file heur_clique.c.

Function Documentation

◆ SCIP_DECL_SORTPTRCOMP()

static SCIP_DECL_SORTPTRCOMP ( varObjSort  )
static

comparison method for sorting variables by non-decreasing index

Definition at line 107 of file heur_clique.c.

◆ stableSortBinvars()

static SCIP_RETCODE stableSortBinvars ( SCIP *  scip,
SCIP_VAR **  binvars,
int  nbinvars,
int *  cliquepartition,
int  ncliques 
)
static

sort the binary variable array w.r.t. the clique partition; thereby ensure the current order within the cliques are not changed

Parameters
scipSCIP data structure
binvarsarray of binary variables to sort
nbinvarsnumber of binary variables
cliquepartitionclique partition to use
ncliquesnumber of cliques

Definition at line 130 of file heur_clique.c.

References applyCliqueFixings(), BMSclearMemoryArray, BMScopyMemoryArray, NULL, SCIP_CALL, SCIP_OKAY, SCIPallocBufferArray, SCIPfreeBufferArray, and SCIPvarGetObj().

◆ applyCliqueFixings()

static SCIP_RETCODE applyCliqueFixings ( SCIP *  scip,
SCIP_HEURDATA *  heurdata,
SCIP_VAR **  binvars,
int  nbinvars,
int *  cliquepartition,
int  ncliques,
SCIP_VAR **  onefixvars,
int *  nonefixvars,
SCIP_SOL *  sol,
int *  probingdepthofonefix,
SCIP_Bool *  cutoff,
SCIP_RESULT *  result 
)
static

apply clique fixing using probing

Parameters
sciporiginal SCIP data structure
heurdatastructure containing heurdata
binvarsbinary variables order w.r.t. to clique partition
nbinvarsnumber of binary variables
cliquepartitionclique partition of all binary variables
ncliquesnumber of cliques
onefixvarsarray to store all variables which are stored to one
nonefixvarspointer to store the number of variables fixed to one
solworking solution
probingdepthofonefixpointer to store in which depth the last fixing to was applied
cutoffpointer to store whether the propagation stopped with infeasibility
resultpointer to store the result (solution found)

Definition at line 232 of file heur_clique.c.

References createNewSol(), FALSE, NULL, SCIP_Bool, SCIP_CALL, SCIP_FOUNDSOL, SCIP_MAXTREEDEPTH, SCIP_OKAY, SCIPdebugMsg, SCIPfixVarProbing(), SCIPgetDepth(), SCIPgetProbingDepth(), SCIPgetSolOrigObj(), SCIPisStopped(), SCIPlinkCurrentSol(), SCIPnewProbingNode(), SCIPpropagateProbing(), SCIProundSol(), SCIPtrySol(), SCIPvarGetLbLocal(), SCIPvarGetName(), SCIPvarGetUbLocal(), and TRUE.

Referenced by stableSortBinvars().

◆ createNewSol()

static SCIP_RETCODE createNewSol ( SCIP *  scip,
SCIP *  subscip,
SCIP_VAR **  subvars,
SCIP_SOL *  newsol,
SCIP_SOL *  subsol,
SCIP_Bool *  success 
)
static

creates a new solution for the original problem by copying the solution of the subproblem

Parameters
sciporiginal SCIP data structure
subscipSCIP structure of the subproblem
subvarsthe variables of the subproblem
newsolworking solution
subsolsolution of the subproblem
successused to store whether new solution was found or not

Definition at line 397 of file heur_clique.c.

References FALSE, HEUR_NAME, NULL, SCIP_CALL, SCIP_DECL_HEURCOPY(), SCIP_OKAY, SCIP_Real, SCIPallocBufferArray, SCIPfreeBufferArray, SCIPgetNOrigVars(), SCIPgetSolVals(), SCIPgetVarsData(), SCIPheurGetName(), SCIPsetSolVals(), SCIPtrySol(), and TRUE.

Referenced by applyCliqueFixings().

◆ SCIP_DECL_HEURCOPY()

static SCIP_DECL_HEURCOPY ( heurCopyClique  )
static

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

Definition at line 445 of file heur_clique.c.

Referenced by createNewSol().

◆ SCIP_DECL_HEURFREE()

static SCIP_DECL_HEURFREE ( heurFreeClique  )
static

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

Definition at line 459 of file heur_clique.c.

◆ SCIP_DECL_HEURINIT()

static SCIP_DECL_HEURINIT ( heurInitClique  )
static

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

Definition at line 480 of file heur_clique.c.

◆ SCIP_DECL_HEUREXIT()

static SCIP_DECL_HEUREXIT ( heurExitClique  )
static

deinitialization method of primal heuristic

Definition at line 504 of file heur_clique.c.

◆ SCIP_DECL_HEUREXEC()

static SCIP_DECL_HEUREXEC ( heurExecClique  )
static

execution method of primal heuristic

Definition at line 525 of file heur_clique.c.