heur_localbranching.c File Reference

Detailed Description

Local branching heuristic according to Fischetti and Lodi.

Author

Timo Berthold

Marc Pfetsch

Definition in file heur_localbranching.c.

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

Go to the source code of this file.

Macros
#define	HEUR_NAME   "localbranching"
#define	HEUR_DESC   "local branching heuristic by Fischetti and Lodi"
#define	HEUR_DISPCHAR   'L'
#define	HEUR_PRIORITY   -1102000
#define	HEUR_FREQ   -1
#define	HEUR_FREQOFS   0
#define	HEUR_MAXDEPTH   -1
#define	HEUR_TIMING   SCIP_HEURTIMING_AFTERNODE
#define	HEUR_USESSUBSCIP   TRUE
#define	DEFAULT_NEIGHBORHOODSIZE   18 /* radius of the incumbents neighborhood to be searched */
#define	DEFAULT_NODESOFS   1000 /* number of nodes added to the contingent of the total nodes */
#define	DEFAULT_MAXNODES   10000 /* maximum number of nodes to regard in the subproblem */
#define	DEFAULT_MINIMPROVE   0.01 /* factor by which localbranching should at least improve the incumbent */
#define	DEFAULT_MINNODES   1000 /* minimum number of nodes required to start the subproblem */
#define	DEFAULT_NODESQUOT   0.05 /* contingent of sub problem nodes in relation to original nodes */
#define	DEFAULT_LPLIMFAC   1.5 /* 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	EVENTHDLR_NAME   "Localbranching"
#define	EVENTHDLR_DESC   "LP event handler for "HEUR_NAME" heuristic"
#define	EXECUTE   0
#define	WAITFORNEWSOL   1

Functions
static SCIP_RETCODE	createSubproblem (SCIP *scip, SCIP *subscip, SCIP_VAR **subvars)
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 (eventExecLocalbranching)
static	SCIP_DECL_HEURCOPY (heurCopyLocalbranching)
static	SCIP_DECL_HEURFREE (heurFreeLocalbranching)
static	SCIP_DECL_HEURINIT (heurInitLocalbranching)
static	SCIP_DECL_HEUREXEC (heurExecLocalbranching)
SCIP_RETCODE	SCIPincludeHeurLocalbranching (SCIP *scip)

Macro Definition Documentation

#define HEUR_NAME   "localbranching"

Definition at line 32 of file heur_localbranching.c.

Referenced by SCIP_DECL_HEURCOPY(), SCIP_DECL_HEUREXEC(), and SCIPincludeHeurLocalbranching().

#define HEUR_DESC   "local branching heuristic by Fischetti and Lodi"

Definition at line 33 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

#define HEUR_DISPCHAR   'L'

Definition at line 34 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

#define HEUR_PRIORITY   -1102000

Definition at line 35 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

#define HEUR_FREQ   -1

Definition at line 36 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

#define HEUR_FREQOFS   0

Definition at line 37 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

#define HEUR_MAXDEPTH   -1

Definition at line 38 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

#define HEUR_TIMING   SCIP_HEURTIMING_AFTERNODE

Definition at line 39 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

#define HEUR_USESSUBSCIP   TRUE

does the heuristic use a secondary SCIP instance?

Definition at line 40 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

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

Definition at line 42 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

#define DEFAULT_NODESOFS   1000 /* number of nodes added to the contingent of the total nodes */

Definition at line 43 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

#define DEFAULT_MAXNODES   10000 /* maximum number of nodes to regard in the subproblem */

Definition at line 44 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

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

Definition at line 45 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

#define DEFAULT_MINNODES   1000 /* minimum number of nodes required to start the subproblem */

Definition at line 46 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

#define DEFAULT_NODESQUOT   0.05 /* contingent of sub problem nodes in relation to original nodes */

Definition at line 47 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

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

Definition at line 48 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

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

Definition at line 49 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

#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    */

Definition at line 50 of file heur_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

#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_localbranching.c.

Referenced by SCIPincludeHeurLocalbranching().

#define EVENTHDLR_NAME   "Localbranching"

Definition at line 54 of file heur_localbranching.c.

Referenced by SCIP_DECL_EVENTEXEC(), and SCIP_DECL_HEUREXEC().

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

Definition at line 55 of file heur_localbranching.c.

Referenced by SCIP_DECL_HEUREXEC().

#define EXECUTE   0

Definition at line 58 of file heur_localbranching.c.

Referenced by SCIP_DECL_HEUREXEC().

#define WAITFORNEWSOL   1

Definition at line 59 of file heur_localbranching.c.

Referenced by SCIP_DECL_HEUREXEC(), and SCIP_DECL_HEURINIT().

Function Documentation

static SCIP_RETCODE createSubproblem ( SCIP *  scip, SCIP *  subscip, SCIP_VAR **  subvars  )

static

copies the problem of scip to the problem of subscip - only necessary if uselprows is false

Parameters

scip	SCIP data structure of the original problem
subscip	SCIP data structure of the subproblem
subvars	variables of the subproblem

Definition at line 97 of file heur_localbranching.c.

References FALSE, SCIP_CALL, SCIP_OKAY, SCIP_Real, SCIPaddCons(), SCIPallocBufferArray, SCIPcolGetVar(), SCIPcreateConsLinear(), SCIPfreeBufferArray, SCIPgetLPRowsData(), SCIPreleaseCons(), SCIProwGetCols(), SCIProwGetConstant(), SCIProwGetLhs(), SCIProwGetName(), SCIProwGetNNonz(), SCIProwGetRhs(), SCIProwGetVals(), SCIProwIsLocal(), SCIPvarGetProbindex(), and TRUE.

Referenced by SCIP_DECL_HEUREXEC().

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 156 of file heur_localbranching.c.

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

Referenced by SCIP_DECL_HEUREXEC().

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	SCIP data structure of the original problem
subscip	SCIP data structure of the subproblem
subvars	the variables of the subproblem
heur	the Localbranching heuristic
subsol	solution of the subproblem
success	pointer to store, whether new solution was found

Definition at line 227 of file heur_localbranching.c.

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

Referenced by SCIP_DECL_HEUREXEC().

static SCIP_DECL_EVENTEXEC ( eventExecLocalbranching  )

static

Definition at line 277 of file heur_localbranching.c.

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

static SCIP_DECL_HEURCOPY ( heurCopyLocalbranching  )

static

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

Definition at line 307 of file heur_localbranching.c.

References HEUR_NAME, NULL, SCIP_CALL, SCIP_OKAY, SCIPheurGetName(), and SCIPincludeHeurLocalbranching().

static SCIP_DECL_HEURFREE ( heurFreeLocalbranching  )

static

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

Definition at line 321 of file heur_localbranching.c.

References NULL, SCIP_OKAY, SCIPfreeMemory, SCIPheurGetData(), and SCIPheurSetData().

static SCIP_DECL_HEURINIT ( heurInitLocalbranching  )

static

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

Definition at line 342 of file heur_localbranching.c.

References NULL, SCIP_OKAY, SCIPheurGetData(), and WAITFORNEWSOL.

static SCIP_DECL_HEUREXEC ( heurExecLocalbranching  )

static

execution method of primal heuristic

Definition at line 367 of file heur_localbranching.c.

References addLocalBranchingConstraint(), createNewSol(), createSubproblem(), EVENTHDLR_DESC, EVENTHDLR_NAME, EXECUTE, FALSE, HEUR_NAME, MAX, MIN, NULL, SCIP_Bool, SCIP_CALL, SCIP_DELAYED, SCIP_DIDNOTFIND, SCIP_DIDNOTRUN, SCIP_EVENTTYPE_LPSOLVED, SCIP_FOUNDSOL, SCIP_Longint, SCIP_MAXSTRLEN, SCIP_OKAY, SCIP_PARAMSETTING_FAST, SCIP_PARAMSETTING_OFF, SCIP_PLUGINNOTFOUND, SCIP_Real, SCIP_STATUS_BESTSOLLIMIT, SCIP_STATUS_GAPLIMIT, SCIP_STATUS_INFEASIBLE, SCIP_STATUS_INFORUNBD, SCIP_STATUS_MEMLIMIT, SCIP_STATUS_NODELIMIT, SCIP_STATUS_OPTIMAL, SCIP_STATUS_SOLLIMIT, SCIP_STATUS_STALLNODELIMIT, SCIP_STATUS_TIMELIMIT, SCIP_STATUS_TOTALNODELIMIT, SCIP_STATUS_UNBOUNDED, SCIP_STATUS_UNKNOWN, SCIP_STATUS_USERINTERRUPT, SCIPallocBufferArray, SCIPblkmem(), SCIPcalcHashtableSize(), SCIPcatchEvent(), SCIPcopy(), SCIPcopyCuts(), SCIPcopyVars(), SCIPcreate(), SCIPcreateProb(), SCIPdebug, SCIPdebugMessage, SCIPdropEvent(), SCIPerrorMessage, SCIPfindBranchrule(), SCIPfindConshdlr(), SCIPfindNodesel(), SCIPfree(), SCIPfreeBufferArray, SCIPgetBestSol(), SCIPgetLowerbound(), SCIPgetMemExternEstim(), SCIPgetMemUsed(), SCIPgetNBinVars(), SCIPgetNNodes(), SCIPgetNSols(), SCIPgetProbName(), SCIPgetRealParam(), SCIPgetSolNodenum(), SCIPgetSolOrigObj(), SCIPgetSols(), SCIPgetSolvingTime(), SCIPgetStatus(), SCIPgetUpperbound(), SCIPgetVarsData(), SCIPhashmapCreate(), SCIPhashmapFree(), SCIPhashmapGetImage(), SCIPheurGetData(), SCIPheurGetName(), SCIPheurGetNBestSolsFound(), SCIPheurGetNCalls(), SCIPincludeDefaultPlugins(), SCIPincludeEventhdlrBasic(), SCIPinfinity(), SCIPisInfinity(), SCIPisParamFixed(), SCIPisStopped(), SCIPprintStatistics(), SCIPsetBoolParam(), SCIPsetIntParam(), SCIPsetLongintParam(), SCIPsetObjlimit(), SCIPsetPresolving(), SCIPsetRealParam(), SCIPsetSeparating(), SCIPsetSubscipsOff(), SCIPsnprintf(), SCIPsolGetHeur(), SCIPsolIsOriginal(), SCIPsolve(), SCIPsumepsilon(), SCIPtransformProb(), SCIPwarningMessage(), TRUE, and WAITFORNEWSOL.

SCIP_RETCODE SCIPincludeHeurLocalbranching

(

SCIP *

scip

)

creates the localbranching primal heuristic and includes it in SCIP

Parameters

scip	SCIP data structure

Definition at line 764 of file heur_localbranching.c.

References DEFAULT_COPYCUTS, DEFAULT_LPLIMFAC, DEFAULT_MAXNODES, DEFAULT_MINIMPROVE, DEFAULT_MINNODES, DEFAULT_NEIGHBORHOODSIZE, DEFAULT_NODESOFS, DEFAULT_NODESQUOT, DEFAULT_NWAITINGNODES, DEFAULT_USELPROWS, FALSE, HEUR_DESC, HEUR_DISPCHAR, HEUR_FREQ, HEUR_FREQOFS, HEUR_MAXDEPTH, HEUR_NAME, HEUR_PRIORITY, HEUR_TIMING, HEUR_USESSUBSCIP, NULL, SCIP_CALL, SCIP_OKAY, SCIP_REAL_MAX, SCIPaddBoolParam(), SCIPaddIntParam(), SCIPaddRealParam(), SCIPallocMemory, SCIPincludeHeurBasic(), SCIPsetHeurCopy(), SCIPsetHeurFree(), SCIPsetHeurInit(), and TRUE.

Referenced by SCIP_DECL_HEURCOPY(), and SCIPincludeDefaultPlugins().