Detailed Description

LNS heuristic that combines the incumbent with the LP optimum.

Author: Timo Berthold

Definition in file heur_rins.c.

#include <assert.h>
#include <string.h>
#include "scip/scip.h"
#include "scip/scipdefplugins.h"
#include "scip/cons_linear.h"
#include "scip/heur_rins.h"
#include "scip/pub_misc.h"

Go to the source code of this file.

Macros
#define	HEUR_NAME "rins"

#define	HEUR_DESC "relaxation induced neighborhood search by Danna, Rothberg, and Le Pape"

#define	HEUR_DISPCHAR 'N'

#define	HEUR_PRIORITY -1101000

#define	HEUR_FREQ 25

#define	HEUR_FREQOFS 0

#define	HEUR_MAXDEPTH -1

#define	HEUR_TIMING SCIP_HEURTIMING_AFTERLPNODE

#define	HEUR_USESSUBSCIP TRUE

#define	DEFAULT_NODESOFS 500 /* number of nodes added to the contingent of the total nodes */

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

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

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

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

#define	DEFAULT_NODESQUOT 0.1 /* subproblem nodes in relation to nodes of the original problem */

#define	DEFAULT_LPLIMFAC 2.0 /* factor by which the limit on the number of LP depends on the node limit */

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

#define	DEFAULT_USELPROWS

#define	DEFAULT_COPYCUTS

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

#define	EVENTHDLR_NAME "Rins"

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

Functions
static SCIP_RETCODE	determineFixings (SCIP scip, SCIP_VAR fixedvars, SCIP_Real fixedvals, int nfixedvars, int fixedvarssize, SCIP_Real minfixingrate, SCIP_Bool success)

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

static	SCIP_DECL_EVENTEXEC (eventExecRins)

static SCIP_RETCODE	wrapperRins (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 nfixedvars, SCIP_Longint nnodes)

static	SCIP_DECL_HEURCOPY (heurCopyRins)

static	SCIP_DECL_HEURFREE (heurFreeRins)

static	SCIP_DECL_HEURINIT (heurInitRins)

static	SCIP_DECL_HEUREXEC (heurExecRins)

SCIP_RETCODE	SCIPincludeHeurRins (SCIP *scip)

Macro Definition Documentation

◆ HEUR_NAME

#define HEUR_NAME "rins"

Definition at line 31 of file heur_rins.c.

Referenced by SCIP_DECL_HEURCOPY(), SCIPincludeHeurRins(), and wrapperRins().

◆ HEUR_DESC

#define HEUR_DESC "relaxation induced neighborhood search by Danna, Rothberg, and Le Pape"

Definition at line 32 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ HEUR_DISPCHAR

#define HEUR_DISPCHAR 'N'

Definition at line 33 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ HEUR_PRIORITY

#define HEUR_PRIORITY -1101000

Definition at line 34 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ HEUR_FREQ

#define HEUR_FREQ 25

Definition at line 35 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ HEUR_FREQOFS

#define HEUR_FREQOFS 0

Definition at line 36 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ HEUR_MAXDEPTH

#define HEUR_MAXDEPTH -1

Definition at line 37 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ HEUR_TIMING

#define HEUR_TIMING SCIP_HEURTIMING_AFTERLPNODE

Definition at line 38 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ HEUR_USESSUBSCIP

#define HEUR_USESSUBSCIP TRUE

does the heuristic use a secondary SCIP instance?

Definition at line 39 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ DEFAULT_NODESOFS

#define DEFAULT_NODESOFS 500 /* number of nodes added to the contingent of the total nodes */

Definition at line 41 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ DEFAULT_MAXNODES

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

Definition at line 42 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ DEFAULT_MINNODES

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

Definition at line 43 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ DEFAULT_MINIMPROVE

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

Definition at line 44 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ DEFAULT_MINFIXINGRATE

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

Definition at line 45 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ DEFAULT_NODESQUOT

#define DEFAULT_NODESQUOT 0.1 /* subproblem nodes in relation to nodes of the original problem */

Definition at line 46 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ DEFAULT_LPLIMFAC

#define DEFAULT_LPLIMFAC 2.0 /* factor by which the limit on the number of LP depends on the node limit */

Definition at line 47 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ DEFAULT_NWAITINGNODES

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

Definition at line 48 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ 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 49 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ 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
                                         */

Definition at line 51 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ DEFAULT_USEUCT

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

Definition at line 54 of file heur_rins.c.

Referenced by SCIPincludeHeurRins().

◆ EVENTHDLR_NAME

#define EVENTHDLR_NAME "Rins"

Definition at line 57 of file heur_rins.c.

Referenced by SCIP_DECL_EVENTEXEC(), and wrapperRins().

◆ EVENTHDLR_DESC

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

Definition at line 58 of file heur_rins.c.

Referenced by wrapperRins().

Function Documentation

◆ determineFixings()

static SCIP_RETCODE determineFixings	(	SCIP *	scip,
		SCIP_VAR **	fixedvars,
		SCIP_Real *	fixedvals,
		int *	nfixedvars,
		int	fixedvarssize,
		SCIP_Real	minfixingrate,
		SCIP_Bool *	success
	)

static

determines variable fixings for RINS

RINS fixes variables with matching solution values in the current LP and the incumbent solution

Parameters

scip	original SCIP data structure
fixedvars	array to store source SCIP variables that should be fixed in the copy
fixedvals	array to store fixing values for variables that should be fixed in the copy
nfixedvars	pointer to store the number of variables that RINS can fix
fixedvarssize	size of the buffer arrays to store potential fixings
minfixingrate	percentage of integer variables that have to be fixed
success	pointer to store whether sufficiently many variable fixings were found

Definition at line 97 of file heur_rins.c.

References FALSE, MAX, SCIP_CALL, SCIP_OKAY, SCIP_Real, SCIPgetBestSol(), SCIPgetSolVal(), SCIPgetVarsData(), SCIPisFeasEQ(), SCIPvarGetLPSol(), and TRUE.

Referenced by SCIP_DECL_HEUREXEC().

◆ 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	RINS heuristic structure
subsol	solution of the subproblem
success	used to store whether new solution was found or not

Definition at line 175 of file heur_rins.c.

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

Referenced by wrapperRins().

◆ SCIP_DECL_EVENTEXEC()

static SCIP_DECL_EVENTEXEC ( eventExecRins )

static

Definition at line 417 of file heur_rins.c.

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

Referenced by createNewSol().

◆ wrapperRins()

static SCIP_RETCODE wrapperRins	(	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	nfixedvars,
		SCIP_Longint	nnodes
	)

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
nfixedvars	Number of fixed variables
nnodes	Number of nodes in the b&b tree

Definition at line 223 of file heur_rins.c.

References createNewSol(), EVENTHDLR_DESC, EVENTHDLR_NAME, FALSE, HEUR_NAME, MAX, nnodes, SCIP_Bool, SCIP_CALL, SCIP_CALL_ABORT, SCIP_EVENTTYPE_LPSOLVED, SCIP_FOUNDSOL, SCIP_OKAY, SCIP_PARAMSETTING_FAST, SCIP_PARAMSETTING_OFF, SCIP_PLUGINNOTFOUND, SCIP_Real, SCIP_VERBLEVEL_FULL, SCIP_VERBLEVEL_NONE, SCIPallocBufferArray, SCIPblkmem(), SCIPcatchEvent(), SCIPcopyLargeNeighborhoodSearch(), SCIPcopyLimits(), SCIPdebug, SCIPdropEvent(), SCIPerrorMessage, SCIPfindBranchrule(), SCIPfindConshdlr(), SCIPfindNodesel(), SCIPfreeBufferArray, SCIPgetLowerbound(), SCIPgetNNodes(), SCIPgetNSols(), SCIPgetSols(), SCIPgetUpperbound(), SCIPhashmapCreate(), SCIPhashmapFree(), SCIPhashmapGetImage(), SCIPincludeEventhdlrBasic(), SCIPisInfinity(), SCIPisParamFixed(), SCIPmergeVariableStatistics(), 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 ( heurCopyRins )

static

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

Definition at line 447 of file heur_rins.c.

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

◆ SCIP_DECL_HEURFREE()

static SCIP_DECL_HEURFREE ( heurFreeRins )

static

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

Definition at line 461 of file heur_rins.c.

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

◆ SCIP_DECL_HEURINIT()

static SCIP_DECL_HEURINIT ( heurInitRins )

static

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

Definition at line 482 of file heur_rins.c.

References SCIP_OKAY, and SCIPheurGetData().

◆ SCIP_DECL_HEUREXEC()

static SCIP_DECL_HEUREXEC ( heurExecRins )

static

execution method of primal heuristic

Definition at line 502 of file heur_rins.c.

References determineFixings(), FALSE, nnodes, SCIP_Bool, SCIP_CALL, SCIP_DELAYED, SCIP_DIDNOTFIND, SCIP_DIDNOTRUN, SCIP_Longint, SCIP_LPSOLSTAT_OPTIMAL, SCIP_OKAY, SCIP_Real, SCIPallocBufferArray, SCIPcheckCopyLimits(), SCIPcreate(), SCIPdebugMsg, SCIPfree(), SCIPfreeBufferArray, SCIPgetBestSol(), SCIPgetCutoffbound(), SCIPgetLPObjval(), SCIPgetLPSolstat(), SCIPgetNNodes(), SCIPgetNSols(), SCIPgetSolNodenum(), SCIPgetVarsData(), SCIPhasCurrentNodeLP(), SCIPheurGetData(), SCIPheurGetNBestSolsFound(), SCIPheurGetNCalls(), SCIPisGE(), SCIPisStopped(), SCIPsolIsOriginal(), and wrapperRins().

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_MINFIXINGRATE

◆ DEFAULT_NODESQUOT

◆ DEFAULT_LPLIMFAC

◆ DEFAULT_NWAITINGNODES

◆ DEFAULT_USELPROWS

◆ DEFAULT_COPYCUTS

◆ DEFAULT_USEUCT

◆ EVENTHDLR_NAME

◆ EVENTHDLR_DESC

Function Documentation

◆ determineFixings()

◆ createNewSol()

◆ SCIP_DECL_EVENTEXEC()

◆ wrapperRins()

◆ SCIP_DECL_HEURCOPY()

◆ SCIP_DECL_HEURFREE()

◆ SCIP_DECL_HEURINIT()

◆ SCIP_DECL_HEUREXEC()