heur_locks.c File Reference

Detailed Description

rounding locks primal heuristic

Author

Michael Winkler

Gerald Gamrath

Definition in file heur_locks.c.

#include <assert.h>
#include <string.h>
#include "scip/heur_locks.h"

Go to the source code of this file.

Macros
#define	HEUR_NAME   "locks"
#define	HEUR_DESC   "heuristic that fixes variables based on their rounding locks"
#define	HEUR_DISPCHAR   'k'
#define	HEUR_PRIORITY   3000
#define	HEUR_FREQ   0
#define	HEUR_FREQOFS   0
#define	HEUR_MAXDEPTH   -1
#define	HEUR_TIMING   SCIP_HEURTIMING_BEFORENODE
#define	HEUR_USESSUBSCIP   TRUE
#define	DEFAULT_MAXNODES   5000LL
#define	DEFAULT_ROUNDUPPROBABILITY   0.67
#define	DEFAULT_MINFIXINGRATE   0.65
#define	DEFAULT_MINIMPROVE   0.01
#define	DEFAULT_MINNODES   500LL
#define	DEFAULT_NODESOFS   500LL
#define	DEFAULT_NODESQUOT   0.1
#define	DEFAULT_MAXPROPROUNDS   2
#define	DEFAULT_UPDATELOCKS   TRUE
#define	DEFAULT_COPYCUTS   TRUE
#define	DEFAULT_USEFINALSUBMIP   TRUE
#define	DEFAULT_RANDSEED   73
#define	heurInitsolLocks   NULL
#define	heurExitsolLocks   NULL

Functions
static SCIP_RETCODE	createNewSol (SCIP *scip, SCIP *subscip, SCIP_VAR **subvars, SCIP_SOL *newsol, SCIP_SOL *subsol, SCIP_Bool *success)
static	SCIP_DECL_HEURCOPY (heurCopyLocks)
static	SCIP_DECL_HEURFREE (heurFreeLocks)
static	SCIP_DECL_HEURINIT (heurInitLocks)
static	SCIP_DECL_HEUREXIT (heurExitLocks)
SCIP_RETCODE	SCIPapplyLockFixings (SCIP *scip, SCIP_HEURDATA *heurdata, SCIP_Bool *cutoff, SCIP_Bool *allrowsfulfilled)
static	SCIP_DECL_HEUREXEC (heurExecLocks)
SCIP_RETCODE	SCIPincludeHeurLocks (SCIP *scip)

Macro Definition Documentation

HEUR_NAME

#define HEUR_NAME   "locks"

Definition at line 29 of file heur_locks.c.

Referenced by SCIP_DECL_HEUREXEC(), and SCIPapplyLockFixings().

HEUR_DESC

#define HEUR_DESC   "heuristic that fixes variables based on their rounding locks"

Definition at line 30 of file heur_locks.c.

HEUR_DISPCHAR

#define HEUR_DISPCHAR   'k'

Definition at line 31 of file heur_locks.c.

HEUR_PRIORITY

#define HEUR_PRIORITY   3000

Definition at line 32 of file heur_locks.c.

HEUR_FREQ

#define HEUR_FREQ   0

Definition at line 33 of file heur_locks.c.

HEUR_FREQOFS

#define HEUR_FREQOFS   0

Definition at line 34 of file heur_locks.c.

HEUR_MAXDEPTH

#define HEUR_MAXDEPTH   -1

Definition at line 35 of file heur_locks.c.

HEUR_TIMING

#define HEUR_TIMING   SCIP_HEURTIMING_BEFORENODE

Definition at line 36 of file heur_locks.c.

HEUR_USESSUBSCIP

#define HEUR_USESSUBSCIP   TRUE

does the heuristic use a secondary SCIP instance?

Definition at line 37 of file heur_locks.c.

DEFAULT_MAXNODES

#define DEFAULT_MAXNODES   5000LL

maximum number of nodes to regard in the subproblem

Definition at line 39 of file heur_locks.c.

DEFAULT_ROUNDUPPROBABILITY

#define DEFAULT_ROUNDUPPROBABILITY   0.67

probability for rounding a variable up in case of ties

Definition at line 40 of file heur_locks.c.

DEFAULT_MINFIXINGRATE

#define DEFAULT_MINFIXINGRATE   0.65

minimum percentage of variables that have to be fixed

Definition at line 41 of file heur_locks.c.

DEFAULT_MINIMPROVE

#define DEFAULT_MINIMPROVE   0.01

factor by which locks heuristic should at least improve the incumbent

Definition at line 42 of file heur_locks.c.

DEFAULT_MINNODES

#define DEFAULT_MINNODES   500LL

minimum number of nodes to regard in the subproblem

Definition at line 47 of file heur_locks.c.

DEFAULT_NODESOFS

#define DEFAULT_NODESOFS   500LL

number of nodes added to the contingent of the total nodes

Definition at line 48 of file heur_locks.c.

DEFAULT_NODESQUOT

#define DEFAULT_NODESQUOT   0.1

subproblem nodes in relation to nodes of the original problem

Definition at line 49 of file heur_locks.c.

DEFAULT_MAXPROPROUNDS

#define DEFAULT_MAXPROPROUNDS   2

maximum number of propagation rounds during probing

Definition at line 50 of file heur_locks.c.

DEFAULT_UPDATELOCKS

#define DEFAULT_UPDATELOCKS   TRUE

should the locks be updated based on LP rows?

Definition at line 51 of file heur_locks.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 52 of file heur_locks.c.

DEFAULT_USEFINALSUBMIP

#define DEFAULT_USEFINALSUBMIP   TRUE

should a final sub-MIP be solved to construct a feasible solution if the LP was not roundable?

Definition at line 55 of file heur_locks.c.

DEFAULT_RANDSEED

#define DEFAULT_RANDSEED   73

initial random seed

Definition at line 58 of file heur_locks.c.

heurInitsolLocks

#define heurInitsolLocks   NULL

Definition at line 198 of file heur_locks.c.

heurExitsolLocks

#define heurExitsolLocks   NULL

Definition at line 199 of file heur_locks.c.

Function Documentation

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

scip	original SCIP data structure
subscip	SCIP structure of the subproblem
subvars	the variables of the subproblem
newsol	working solution
subsol	solution of the subproblem
success	used to store whether new solution was found or not

Definition at line 86 of file heur_locks.c.

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

Referenced by SCIP_DECL_HEUREXEC().

SCIP_DECL_HEURCOPY()

static SCIP_DECL_HEURCOPY ( heurCopyLocks  )

static

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

Definition at line 130 of file heur_locks.c.

Referenced by createNewSol().

SCIP_DECL_HEURFREE()

static SCIP_DECL_HEURFREE ( heurFreeLocks  )

static

free method for primal heuristic plugins (called when SCIP is exiting)

Definition at line 144 of file heur_locks.c.

SCIP_DECL_HEURINIT()

static SCIP_DECL_HEURINIT ( heurInitLocks  )

static

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

Definition at line 162 of file heur_locks.c.

SCIP_DECL_HEUREXIT()

static SCIP_DECL_HEUREXIT ( heurExitLocks  )

static

deinitialization method of primal heuristic (called before transformed problem is freed)

Definition at line 182 of file heur_locks.c.

SCIPapplyLockFixings()

SCIP_RETCODE SCIPapplyLockFixings	(	SCIP *	scip,
		SCIP_HEURDATA *	heurdata,
		SCIP_Bool *	cutoff,
		SCIP_Bool *	allrowsfulfilled
	)

apply fix-and-propagate scheme based on variable locks

Note

probing mode of SCIP needs to be enabled before

Parameters

scip	SCIP data structure
heurdata	primal heuristic data
cutoff	pointer to store if a cutoff was detected
allrowsfulfilled	pointer to store if all rows became redundant

Definition at line 205 of file heur_locks.c.

References FALSE, HEUR_NAME, REALABS, SCIP_Bool, SCIP_CALL, SCIP_DECL_HEUREXEC(), SCIP_MAXTREEDEPTH, SCIP_OKAY, SCIP_Real, SCIP_VARSTATUS_COLUMN, SCIP_VARTYPE_BINARY, SCIPallocBufferArray, SCIPallocClearBufferArray, SCIPbacktrackProbing(), SCIPcolGetNNonz(), SCIPcolGetRows(), SCIPcolGetVals(), SCIPcolGetVar(), SCIPconshdlrGetNCheckConss(), SCIPdebug, SCIPdebugMsg, SCIPduplicateBufferArray, SCIPfindConshdlr(), SCIPfindHeur(), SCIPfixVarProbing(), SCIPfreeBufferArray, SCIPfreeBufferArrayNull, SCIPgetDepth(), SCIPgetLPRowsData(), SCIPgetNCheckConss(), SCIPgetNConss(), SCIPgetNLPRows(), SCIPgetProbingDepth(), SCIPgetRowMaxActivity(), SCIPgetRowMinActivity(), SCIPgetVarsData(), SCIPheurGetData(), SCIPinProbing(), SCIPisFeasGE(), SCIPisFeasGT(), SCIPisFeasLE(), SCIPisFeasLT(), SCIPisInfinity(), SCIPisPositive(), SCIPisStopped(), SCIPnewProbingNode(), SCIPprintRow(), SCIPpropagateProbing(), SCIPrandomGetReal(), SCIProwGetCols(), SCIProwGetLhs(), SCIProwGetLPPos(), SCIProwGetName(), SCIProwGetNNonz(), SCIProwGetRank(), SCIProwGetRhs(), SCIProwGetVals(), SCIPvarGetCol(), SCIPvarGetLbLocal(), SCIPvarGetName(), SCIPvarGetNLocksDown(), SCIPvarGetNLocksUp(), SCIPvarGetObj(), SCIPvarGetProbindex(), SCIPvarGetStatus(), SCIPvarGetType(), SCIPvarGetUbLocal(), and TRUE.

Referenced by applyVbounds(), and SCIP_DECL_HEUREXEC().

SCIP_DECL_HEUREXEC()

static SCIP_DECL_HEUREXEC ( heurExecLocks  )

static

execution method of primal heuristic

Definition at line 670 of file heur_locks.c.

References createNewSol(), FALSE, HEUR_NAME, SCIP_Bool, SCIP_CALL, SCIP_CALL_ABORT, SCIP_DIDNOTFIND, SCIP_FOUNDSOL, SCIP_Longint, SCIP_LPSOLSTAT_INFEASIBLE, SCIP_LPSOLSTAT_OBJLIMIT, SCIP_LPSOLSTAT_OPTIMAL, SCIP_OKAY, SCIP_PARAMSETTING_FAST, SCIP_PARAMSETTING_OFF, SCIP_Real, SCIPallocBufferArray, SCIPapplyLockFixings(), SCIPblkmem(), SCIPcheckCopyLimits(), SCIPcheckSol(), SCIPconstructLP(), SCIPcopy(), SCIPcopyCuts(), SCIPcopyLimits(), SCIPcreate(), SCIPcreateSol(), SCIPcutoffNode(), SCIPdebug, SCIPdebugMsg, SCIPenableVarHistory(), SCIPendProbing(), SCIPfindBranchrule(), SCIPfindConshdlr(), SCIPflushLP(), SCIPfree(), SCIPfreeBufferArray, SCIPfreeSol(), SCIPgetBoolParam(), SCIPgetCurrentNode(), SCIPgetLowerbound(), SCIPgetLPObjval(), SCIPgetLPSolstat(), SCIPgetNConss(), SCIPgetNLPIterations(), SCIPgetNLPRows(), SCIPgetNNodes(), SCIPgetNPseudoBranchCands(), SCIPgetNSols(), SCIPgetNVars(), SCIPgetSols(), SCIPgetSolvingTime(), SCIPgetStatus(), SCIPgetUpperbound(), SCIPgetVarsData(), SCIPhashmapCreate(), SCIPhashmapFree(), SCIPhashmapGetImage(), SCIPheurGetData(), SCIPheurGetNBestSolsFound(), SCIPheurGetNCalls(), SCIPincludeHeurLocks(), SCIPisInfinity(), SCIPisParamFixed(), SCIPisStopped(), SCIPlinkLPSol(), SCIPpresolve(), SCIPprintSol(), SCIPprintStatistics(), SCIProundSol(), SCIPsetBoolParam(), SCIPsetIntParam(), SCIPsetLongintParam(), SCIPsetObjlimit(), SCIPsetPresolving(), SCIPsetSeparating(), SCIPsetSubscipsOff(), SCIPsolve(), SCIPsolveProbingLP(), SCIPstartProbing(), SCIPsumepsilon(), SCIPtrySol(), SCIPwarningMessage(), and TRUE.

Referenced by SCIPapplyLockFixings().