Detailed Description

DINS primal heuristic (according to Ghosh)

Author: Timo Berthold; Robert Waniek

Definition in file heur_dins.c.

#include <assert.h>
#include <string.h>
#include "scip/scip.h"
#include "scip/cons_linear.h"
#include "scip/heur_dins.h"

Go to the source code of this file.

Macros
#define	HEUR_NAME "dins"

#define	HEUR_DESC "distance induced neighborhood search by Ghosh"

#define	HEUR_DISPCHAR 'D'

#define	HEUR_PRIORITY -1105000

#define	HEUR_FREQ -1

#define	HEUR_FREQOFS 0

#define	HEUR_MAXDEPTH -1

#define	HEUR_TIMING SCIP_HEURTIMING_AFTERLPNODE

#define	HEUR_USESSUBSCIP TRUE

#define	DEFAULT_NODESOFS 5000LL /* number of nodes added to the contingent of the total nodes */

#define	DEFAULT_MAXNODES 5000LL /* maximum number of nodes to regard in the subproblem */

#define	DEFAULT_MINNODES 50LL /* minimum number of nodes to regard in the subproblem */

#define	DEFAULT_MINIMPROVE 0.01 /* factor by which DINS should at least improve the incumbent */

#define	DEFAULT_NODESQUOT 0.05 /* subproblem nodes in relation to nodes of the original problem */

#define	DEFAULT_LPLIMFAC 1.5 /* factor by which the limit on the number of LP depends on the node limit */

#define	DEFAULT_MINFIXINGRATE 0.3 /* minimum percentage of integer variables that have to be fixed */

#define	DEFAULT_NWAITINGNODES 200LL /* number of nodes without incumbent change that heuristic should wait */

#define	DEFAULT_NEIGHBORHOODSIZE 18 /* radius of the incumbents neighborhood to be searched */

#define	DEFAULT_SOLNUM 5 /* number of pool-solutions to be checked for flag array update */

#define	DEFAULT_USELPROWS

#define	DEFAULT_COPYCUTS

#define	DEFAULT_BESTSOLLIMIT 3 /* limit on number of improving incumbent solutions in sub-CIP */

#define	DEFAULT_USEUCT FALSE /* should uct node selection be used at the beginning of the search? */

#define	EVENTHDLR_NAME "Dins"

#define	EVENTHDLR_DESC "LP event handler for " HEUR_NAME " heuristic"

Functions
static void	computeIntegerVariableBounds (SCIP scip, SCIP_VAR var, SCIP_Real lbptr, SCIP_Real ubptr)

static SCIP_RETCODE	determineVariableFixings (SCIP scip, SCIP_HEUR heur, SCIP_HEURDATA heurdata, SCIP_VAR vars, SCIP_VAR fixedvars, SCIP_Real fixedvals, int nbinvars, int nintvars, int binfixings, int intfixings)

static SCIP_RETCODE	reboundIntegerVariables (SCIP scip, SCIP subscip, SCIP_VAR vars, SCIP_VAR subvars, int nbinvars, int nintvars)

static SCIP_RETCODE	addLocalBranchingConstraint (SCIP scip, SCIP subscip, SCIP_VAR *subvars, SCIP_HEURDATA heurdata)

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

static	SCIP_DECL_EVENTEXEC (eventExecDins)

static SCIP_RETCODE	wrapperDins (SCIP scip, SCIP subscip, SCIP_HEUR heur, SCIP_HEURDATA heurdata, SCIP_VAR vars, SCIP_VAR fixedvars, SCIP_Real fixedvals, SCIP_RESULT result, int nvars, int nbinvars, int nintvars, int binfixings, int intfixings, SCIP_Longint nsubnodes)

static	SCIP_DECL_HEURCOPY (heurCopyDins)

static	SCIP_DECL_HEURFREE (heurFreeDins)

static	SCIP_DECL_HEURINITSOL (heurInitsolDins)

static	SCIP_DECL_HEUREXITSOL (heurExitsolDins)

static	SCIP_DECL_HEUREXEC (heurExecDins)

SCIP_RETCODE	SCIPincludeHeurDins (SCIP *scip)

Macro Definition Documentation

◆ HEUR_NAME

#define HEUR_NAME "dins"

Definition at line 30 of file heur_dins.c.

Referenced by SCIP_DECL_HEURCOPY(), SCIPincludeHeurDins(), and wrapperDins().

◆ HEUR_DESC

#define HEUR_DESC "distance induced neighborhood search by Ghosh"

Definition at line 31 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ HEUR_DISPCHAR

#define HEUR_DISPCHAR 'D'

Definition at line 32 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ HEUR_PRIORITY

#define HEUR_PRIORITY -1105000

Definition at line 33 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ HEUR_FREQ

#define HEUR_FREQ -1

Definition at line 34 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ HEUR_FREQOFS

#define HEUR_FREQOFS 0

Definition at line 35 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ HEUR_MAXDEPTH

#define HEUR_MAXDEPTH -1

Definition at line 36 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ HEUR_TIMING

#define HEUR_TIMING SCIP_HEURTIMING_AFTERLPNODE

Definition at line 37 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ HEUR_USESSUBSCIP

#define HEUR_USESSUBSCIP TRUE

does the heuristic use a secondary SCIP instance?

Definition at line 38 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ DEFAULT_NODESOFS

#define DEFAULT_NODESOFS 5000LL /* number of nodes added to the contingent of the total nodes */

Definition at line 40 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ DEFAULT_MAXNODES

#define DEFAULT_MAXNODES 5000LL /* maximum number of nodes to regard in the subproblem */

Definition at line 41 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ DEFAULT_MINNODES

#define DEFAULT_MINNODES 50LL /* minimum number of nodes to regard in the subproblem */

Definition at line 42 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ DEFAULT_MINIMPROVE

#define DEFAULT_MINIMPROVE 0.01 /* factor by which DINS should at least improve the incumbent */

Definition at line 43 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ DEFAULT_NODESQUOT

#define DEFAULT_NODESQUOT 0.05 /* subproblem nodes in relation to nodes of the original problem */

Definition at line 44 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ DEFAULT_LPLIMFAC

#define DEFAULT_LPLIMFAC 1.5 /* factor by which the limit on the number of LP depends on the node limit */

Definition at line 45 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ DEFAULT_MINFIXINGRATE

#define DEFAULT_MINFIXINGRATE 0.3 /* minimum percentage of integer variables that have to be fixed */

Definition at line 46 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ DEFAULT_NWAITINGNODES

#define DEFAULT_NWAITINGNODES 200LL /* number of nodes without incumbent change that heuristic should wait */

Definition at line 47 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ DEFAULT_NEIGHBORHOODSIZE

#define DEFAULT_NEIGHBORHOODSIZE 18 /* radius of the incumbents neighborhood to be searched */

Definition at line 48 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ DEFAULT_SOLNUM

#define DEFAULT_SOLNUM 5 /* number of pool-solutions to be checked for flag array update */

Definition at line 49 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ DEFAULT_USELPROWS

#define DEFAULT_USELPROWS

Value:

FALSE /* should subproblem be created out of the rows in the LP rows,

* otherwise, the copy constructors of the constraints handlers are used */

FALSE

#define FALSE

Definition: def.h:64

Definition at line 50 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ DEFAULT_COPYCUTS

#define DEFAULT_COPYCUTS

Value:

TRUE /* if DEFAULT_USELPROWS is FALSE, then should all active cuts from the cutpool

* of the original scip be copied to constraints of the subscip */

TRUE

#define TRUE

Definition: def.h:63

Definition at line 52 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ DEFAULT_BESTSOLLIMIT

#define DEFAULT_BESTSOLLIMIT 3 /* limit on number of improving incumbent solutions in sub-CIP */

Definition at line 55 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ DEFAULT_USEUCT

#define DEFAULT_USEUCT FALSE /* should uct node selection be used at the beginning of the search? */

Definition at line 56 of file heur_dins.c.

Referenced by SCIPincludeHeurDins().

◆ EVENTHDLR_NAME

#define EVENTHDLR_NAME "Dins"

Definition at line 60 of file heur_dins.c.

Referenced by SCIP_DECL_EVENTEXEC(), and wrapperDins().

◆ EVENTHDLR_DESC

#define EVENTHDLR_DESC "LP event handler for " HEUR_NAME " heuristic"

Definition at line 61 of file heur_dins.c.

Referenced by wrapperDins().

Function Documentation

◆ computeIntegerVariableBounds()

static void computeIntegerVariableBounds	(	SCIP *	scip,
		SCIP_VAR *	var,
		SCIP_Real *	lbptr,
		SCIP_Real *	ubptr
	)

static

compute tightened bounds for integer variables depending on how much the LP and the incumbent solution values differ

Parameters

scip	SCIP data structure of the original problem
var	the variable for which bounds should be computed
lbptr	pointer to store the lower bound in the DINS sub-SCIP
ubptr	pointer to store the upper bound in the DINS sub-SCIP

Definition at line 100 of file heur_dins.c.

References MAX, REALABS, SCIP_Real, SCIP_VARTYPE_INTEGER, SCIPfeasCeil(), SCIPfeasFloor(), SCIPgetBestSol(), SCIPgetSolVal(), SCIPisFeasEQ(), SCIPvarGetLbGlobal(), SCIPvarGetLPSol(), SCIPvarGetType(), and SCIPvarGetUbGlobal().

Referenced by determineVariableFixings(), and reboundIntegerVariables().

◆ determineVariableFixings()

static SCIP_RETCODE determineVariableFixings	(	SCIP *	scip,
		SCIP_HEUR *	heur,
		SCIP_HEURDATA *	heurdata,
		SCIP_VAR **	vars,
		SCIP_VAR **	fixedvars,
		SCIP_Real *	fixedvals,
		int	nbinvars,
		int	nintvars,
		int *	binfixings,
		int *	intfixings
	)

static

creates a subproblem for subscip by fixing a number of variables

Parameters

scip	SCIP data structure of the original problem
heur	DINS heuristic structure
heurdata	heuristic data structure
vars	variables of the original problem
fixedvars	array to store variables that should be fixed in the sub-SCIP
fixedvals	array to store fixing values for fixed variables
nbinvars	number of binary variables of problem and subproblem
nintvars	number of general integer variables of problem and subproblem
binfixings	pointer to store number of binary variables that should be fixed
intfixings	pointer to store number of integer variables that should be fixed

Definition at line 175 of file heur_dins.c.

References computeIntegerVariableBounds(), SCIP_Bool, SCIP_CALL, SCIP_Longint, SCIP_OKAY, SCIP_Real, SCIPcalcMemGrowSize(), SCIPgetBestSol(), SCIPgetNSols(), SCIPgetNSolsFound(), SCIPgetSolHeur(), SCIPgetSols(), SCIPgetSolVal(), SCIPisFeasEQ(), SCIPreallocBlockMemoryArray, SCIPvarGetLPSol(), SCIPvarGetRootSol(), and TRUE.

Referenced by SCIP_DECL_HEUREXEC().

◆ reboundIntegerVariables()

static SCIP_RETCODE reboundIntegerVariables	(	SCIP *	scip,
		SCIP *	subscip,
		SCIP_VAR **	vars,
		SCIP_VAR **	subvars,
		int	nbinvars,
		int	nintvars
	)

static

creates a subproblem for subscip by fixing a number of variables

Parameters

scip	SCIP data structure of the original problem
subscip	SCIP data structure of the subproblem
vars	variables of the original problem
subvars	variables of the DINS sub-SCIP
nbinvars	number of binary variables of problem and subproblem
nintvars	number of general integer variables of problem and subproblem

Definition at line 305 of file heur_dins.c.

References computeIntegerVariableBounds(), SCIP_CALL, SCIP_OKAY, SCIP_Real, SCIPchgVarLbGlobal(), SCIPchgVarUbGlobal(), SCIPisFeasEQ(), SCIPvarGetLbGlobal(), and SCIPvarGetUbGlobal().

Referenced by wrapperDins().

◆ addLocalBranchingConstraint()

static SCIP_RETCODE addLocalBranchingConstraint	(	SCIP *	scip,
		SCIP *	subscip,
		SCIP_VAR **	subvars,
		SCIP_HEURDATA *	heurdata
	)

static

create the extra constraint of local branching and add it to subscip

Parameters

scip	SCIP data structure of the original problem
subscip	SCIP data structure of the subproblem
subvars	variables of the subproblem
heurdata	heuristic's data structure

Definition at line 339 of file heur_dins.c.

References FALSE, SCIP_CALL, SCIP_MAXSTRLEN, SCIP_OKAY, SCIP_Real, SCIP_VARTYPE_BINARY, SCIPaddCons(), SCIPallocBufferArray, SCIPcreateConsLinear(), SCIPfreeBufferArray, SCIPgetBestSol(), SCIPgetProbName(), SCIPgetSolVal(), SCIPgetVarsData(), SCIPisFeasEQ(), SCIPisFeasIntegral(), SCIPreleaseCons(), SCIPsnprintf(), SCIPvarGetLbGlobal(), SCIPvarGetType(), SCIPvarGetUbGlobal(), and TRUE.

Referenced by wrapperDins().

◆ createNewSol()

static SCIP_RETCODE createNewSol	(	SCIP *	scip,
		SCIP *	subscip,
		SCIP_VAR **	subvars,
		SCIP_HEUR *	heur,
		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
heur	DINS heuristic structure
subsol	solution of the subproblem
success	used to store whether new solution was found or not

Definition at line 412 of file heur_dins.c.

References FALSE, SCIP_CALL, SCIP_DECL_EVENTEXEC(), SCIP_OKAY, SCIP_Real, SCIPallocBufferArray, SCIPcreateSol(), SCIPdebugMsg, SCIPfreeBufferArray, SCIPgetNOrigVars(), SCIPgetSolVals(), SCIPgetVarsData(), SCIPsetSolVals(), SCIPtrySolFree(), and TRUE.

Referenced by wrapperDins().

◆ SCIP_DECL_EVENTEXEC()

static SCIP_DECL_EVENTEXEC ( eventExecDins )

static

Definition at line 693 of file heur_dins.c.

References EVENTHDLR_NAME, SCIP_CALL, SCIP_EVENTTYPE_LPSOLVED, SCIP_OKAY, SCIPdebugMsg, SCIPeventGetType(), SCIPeventhdlrGetName(), SCIPgetNLPs(), and SCIPinterruptSolve().

Referenced by createNewSol().

◆ wrapperDins()

static SCIP_RETCODE wrapperDins	(	SCIP *	scip,
		SCIP *	subscip,
		SCIP_HEUR *	heur,
		SCIP_HEURDATA *	heurdata,
		SCIP_VAR **	vars,
		SCIP_VAR **	fixedvars,
		SCIP_Real *	fixedvals,
		SCIP_RESULT *	result,
		int	nvars,
		int	nbinvars,
		int	nintvars,
		int	binfixings,
		int	intfixings,
		SCIP_Longint	nsubnodes
	)

static

wrapper for the part of heuristic that runs a subscip. Wrapper is needed to avoid possible ressource leaks

Parameters

scip	original SCIP data structure
subscip	SCIP structure of the subproblem
heur	Heuristic pointer
heurdata	Heuristic's data
vars	original problem's variables
fixedvars	Fixed variables of original SCIP
fixedvals	Fixed values of original SCIP
result	Result pointer
nvars	Number of variables
nbinvars	Number of binary variables in original SCIP
nintvars	Number of integer variables in original SCIP
binfixings	Number of binary fixing in original SCIP
intfixings	Number of integer fixings in original SCIP
nsubnodes	Number of nodes in the subscip

Definition at line 464 of file heur_dins.c.

References addLocalBranchingConstraint(), createNewSol(), EVENTHDLR_DESC, EVENTHDLR_NAME, FALSE, HEUR_NAME, MAX, reboundIntegerVariables(), SCIP_Bool, SCIP_CALL, SCIP_CALL_ABORT, SCIP_EVENTTYPE_LPSOLVED, SCIP_FOUNDSOL, SCIP_OKAY, SCIP_PARAMSETTING_FAST, SCIP_PARAMSETTING_OFF, SCIP_PLUGINNOTFOUND, SCIP_Real, SCIPallocBufferArray, SCIPblkmem(), SCIPcatchEvent(), SCIPcopyLargeNeighborhoodSearch(), SCIPcopyLimits(), SCIPdebug, SCIPdebugMsg, SCIPdropEvent(), SCIPerrorMessage, SCIPfindBranchrule(), SCIPfindConshdlr(), SCIPfindNodesel(), SCIPfreeBufferArray, SCIPgetLowerbound(), SCIPgetNBinVars(), SCIPgetNConss(), SCIPgetNIntVars(), SCIPgetNNodes(), SCIPgetNSols(), SCIPgetNVars(), SCIPgetSols(), SCIPgetUpperbound(), SCIPhashmapCreate(), SCIPhashmapFree(), SCIPhashmapGetImage(), SCIPincludeEventhdlrBasic(), SCIPisInfinity(), SCIPisParamFixed(), SCIPprintStatistics(), SCIPsetBoolParam(), SCIPsetCharParam(), SCIPsetIntParam(), SCIPsetLongintParam(), SCIPsetObjlimit(), SCIPsetPresolving(), SCIPsetSeparating(), SCIPsetSubscipsOff(), SCIPsolve(), SCIPsumepsilon(), SCIPtransformProb(), and TRUE.

Referenced by SCIP_DECL_HEUREXEC().

◆ SCIP_DECL_HEURCOPY()

static SCIP_DECL_HEURCOPY ( heurCopyDins )

static

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

Definition at line 723 of file heur_dins.c.

References HEUR_NAME, SCIP_CALL, SCIP_OKAY, SCIPheurGetName(), and SCIPincludeHeurDins().

◆ SCIP_DECL_HEURFREE()

static SCIP_DECL_HEURFREE ( heurFreeDins )

static

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

Definition at line 737 of file heur_dins.c.

References SCIP_OKAY, SCIPfreeBlockMemory, SCIPheurGetData(), and SCIPheurSetData().

◆ SCIP_DECL_HEURINITSOL()

static SCIP_DECL_HEURINITSOL ( heurInitsolDins )

static

solving process initialization method of primal heuristic (called when branch and bound process is about to begin)

Definition at line 758 of file heur_dins.c.

References SCIP_CALL, SCIP_OKAY, SCIPallocBlockMemoryArray, SCIPgetNBinVars(), SCIPheurGetData(), and TRUE.

◆ SCIP_DECL_HEUREXITSOL()

static SCIP_DECL_HEUREXITSOL ( heurExitsolDins )

static

solving process deinitialization method of primal heuristic (called before branch and bound process data is freed)

Definition at line 789 of file heur_dins.c.

References SCIP_OKAY, SCIPfreeBlockMemoryArray, and SCIPheurGetData().

◆ SCIP_DECL_HEUREXEC()

static SCIP_DECL_HEUREXEC ( heurExecDins )

static

execution method of primal heuristic

Definition at line 810 of file heur_dins.c.

References determineVariableFixings(), MAX, SCIP_Bool, SCIP_CALL, SCIP_DELAYED, SCIP_DIDNOTFIND, SCIP_DIDNOTRUN, SCIP_Longint, SCIP_LPSOLSTAT_OPTIMAL, SCIP_OKAY, SCIP_Real, SCIPallocBufferArray, SCIPcheckCopyLimits(), SCIPcreate(), SCIPfree(), SCIPfreeBufferArray, SCIPgetBestSol(), SCIPgetCutoffbound(), SCIPgetLPObjval(), SCIPgetLPSolstat(), SCIPgetNNodes(), SCIPgetNSols(), SCIPgetSolNodenum(), SCIPgetVarsData(), SCIPhasCurrentNodeLP(), SCIPheurGetData(), SCIPheurGetNBestSolsFound(), SCIPheurGetNCalls(), SCIPisGE(), SCIPisStopped(), and wrapperDins().

SCIP

Detailed Description

Macros

Functions

Macro Definition Documentation

◆ HEUR_NAME

◆ HEUR_DESC

◆ HEUR_DISPCHAR

◆ HEUR_PRIORITY

◆ HEUR_FREQ

◆ HEUR_FREQOFS

◆ HEUR_MAXDEPTH

◆ HEUR_TIMING

◆ HEUR_USESSUBSCIP

◆ DEFAULT_NODESOFS

◆ DEFAULT_MAXNODES

◆ DEFAULT_MINNODES

◆ DEFAULT_MINIMPROVE

◆ DEFAULT_NODESQUOT

◆ DEFAULT_LPLIMFAC

◆ DEFAULT_MINFIXINGRATE

◆ DEFAULT_NWAITINGNODES

◆ DEFAULT_NEIGHBORHOODSIZE

◆ DEFAULT_SOLNUM

◆ DEFAULT_USELPROWS

◆ DEFAULT_COPYCUTS

◆ DEFAULT_BESTSOLLIMIT

◆ DEFAULT_USEUCT

◆ EVENTHDLR_NAME

◆ EVENTHDLR_DESC

Function Documentation

◆ computeIntegerVariableBounds()

◆ determineVariableFixings()

◆ reboundIntegerVariables()

◆ addLocalBranchingConstraint()

◆ createNewSol()

◆ SCIP_DECL_EVENTEXEC()

◆ wrapperDins()

◆ SCIP_DECL_HEURCOPY()

◆ SCIP_DECL_HEURFREE()

◆ SCIP_DECL_HEURINITSOL()

◆ SCIP_DECL_HEUREXITSOL()

◆ SCIP_DECL_HEUREXEC()