heur_gcgrins.c File Reference

Detailed Description

LNS heuristic that combines the incumbent with the LP optimum.

Author

Timo Berthold

Christian Puchert

Definition in file heur_gcgrins.c.

#include <assert.h>
#include <string.h>
#include "heur_gcgrins.h"
#include "gcg.h"
#include "scip/scipdefplugins.h"
#include "scip/cons_linear.h"

Go to the source code of this file.

Data Structures
struct	SCIP_HeurData

Macros
#define	HEUR_NAME   "gcgrins"
#define	HEUR_DESC   "relaxation induced neighborhood search by Danna, Rothberg, and Le Pape"
#define	HEUR_DISPCHAR   'N'
#define	HEUR_PRIORITY   -1101000
#define	HEUR_FREQ   20
#define	HEUR_FREQOFS   5
#define	HEUR_MAXDEPTH   -1
#define	HEUR_TIMING   SCIP_HEURTIMING_AFTERNODE
#define	HEUR_USESSUBSCIP   TRUE
#define	DEFAULT_NODESOFS   500
#define	DEFAULT_MAXNODES   5000
#define	DEFAULT_MINNODES   500
#define	DEFAULT_MINIMPROVE   0.01
#define	DEFAULT_MINFIXINGRATE   0.0
#define	DEFAULT_NODESQUOT   0.1
#define	DEFAULT_NWAITINGNODES   200
#define	DEFAULT_USELPROWS   FALSE
#define	DEFAULT_COPYCUTS   TRUE

Functions
static SCIP_RETCODE	createSubproblem (SCIP *scip, SCIP *subscip, SCIP_VAR **subvars, SCIP_Real minfixingrate, SCIP_Bool uselprows, SCIP_Real *intfixingrate, SCIP_Real *zerofixingrate, 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_HEURFREE (heurFreeGcgrins)
static	SCIP_DECL_HEURINIT (heurInitGcgrins)
static	SCIP_DECL_HEUREXEC (heurExecGcgrins)
SCIP_RETCODE	SCIPincludeHeurGcgrins (SCIP *scip)

Macro Definition Documentation

HEUR_NAME

#define HEUR_NAME   "gcgrins"

Definition at line 45 of file heur_gcgrins.c.

HEUR_DESC

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

Definition at line 46 of file heur_gcgrins.c.

HEUR_DISPCHAR

#define HEUR_DISPCHAR   'N'

Definition at line 47 of file heur_gcgrins.c.

HEUR_PRIORITY

#define HEUR_PRIORITY   -1101000

Definition at line 48 of file heur_gcgrins.c.

HEUR_FREQ

#define HEUR_FREQ   20

Definition at line 49 of file heur_gcgrins.c.

HEUR_FREQOFS

#define HEUR_FREQOFS   5

Definition at line 50 of file heur_gcgrins.c.

HEUR_MAXDEPTH

#define HEUR_MAXDEPTH   -1

Definition at line 51 of file heur_gcgrins.c.

HEUR_TIMING

#define HEUR_TIMING   SCIP_HEURTIMING_AFTERNODE

Definition at line 52 of file heur_gcgrins.c.

HEUR_USESSUBSCIP

#define HEUR_USESSUBSCIP   TRUE

does the heuristic use a secondary SCIP instance?

Definition at line 53 of file heur_gcgrins.c.

DEFAULT_NODESOFS

#define DEFAULT_NODESOFS   500

number of nodes added to the contingent of the total nodes

Definition at line 55 of file heur_gcgrins.c.

DEFAULT_MAXNODES

#define DEFAULT_MAXNODES   5000

maximum number of nodes to regard in the subproblem

Definition at line 56 of file heur_gcgrins.c.

DEFAULT_MINNODES

#define DEFAULT_MINNODES   500

minimum number of nodes to regard in the subproblem

Definition at line 57 of file heur_gcgrins.c.

DEFAULT_MINIMPROVE

#define DEFAULT_MINIMPROVE   0.01

factor by which RINS should at least improve the incumbent

Definition at line 58 of file heur_gcgrins.c.

DEFAULT_MINFIXINGRATE

#define DEFAULT_MINFIXINGRATE   0.0

minimum percentage of integer variables that have to be fixed

Definition at line 59 of file heur_gcgrins.c.

DEFAULT_NODESQUOT

#define DEFAULT_NODESQUOT   0.1

subproblem nodes in relation to nodes of the original problem

Definition at line 60 of file heur_gcgrins.c.

DEFAULT_NWAITINGNODES

#define DEFAULT_NWAITINGNODES   200

number of nodes without incumbent change that heuristic should wait

Definition at line 61 of file heur_gcgrins.c.

DEFAULT_USELPROWS

#define DEFAULT_USELPROWS   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 62 of file heur_gcgrins.c.

DEFAULT_COPYCUTS

#define DEFAULT_COPYCUTS   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 64 of file heur_gcgrins.c.

Function Documentation

createSubproblem()

static SCIP_RETCODE createSubproblem ( SCIP *  scip, SCIP *  subscip, SCIP_VAR **  subvars, SCIP_Real  minfixingrate, SCIP_Bool  uselprows, SCIP_Real *  intfixingrate, SCIP_Real *  zerofixingrate, SCIP_Bool *  success  )

static

creates a subproblem for subscip by fixing a number of variables

Parameters

scip	original SCIP data structure
subscip	SCIP data structure for the subproblem
subvars	the variables of the subproblem
minfixingrate	percentage of integer variables that have to be fixed
uselprows	should subproblem be created out of the rows in the LP rows?
intfixingrate	percentage of integers that get actually fixed
zerofixingrate	percentage of variables fixed to zero
success	pointer to store whether the problem was created successfully

Definition at line 106 of file heur_gcgrins.c.

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 243 of file heur_gcgrins.c.

Referenced by SCIP_DECL_HEUREXEC().

SCIP_DECL_HEURFREE()

static SCIP_DECL_HEURFREE ( heurFreeGcgrins  )

static

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

Definition at line 311 of file heur_gcgrins.c.

SCIP_DECL_HEURINIT()

static SCIP_DECL_HEURINIT ( heurInitGcgrins  )

static

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

Definition at line 332 of file heur_gcgrins.c.

SCIP_DECL_HEUREXEC()

static SCIP_DECL_HEUREXEC ( heurExecGcgrins  )

static

execution method of primal heuristic

Definition at line 416 of file heur_gcgrins.c.

References createNewSol(), createSubproblem(), and GCGgetMasterprob().

SCIPincludeHeurGcgrins()

SCIP_RETCODE SCIPincludeHeurGcgrins

(

SCIP *

scip

)

creates the GCG RINS primal heuristic and includes it in SCIP

Parameters

scip	SCIP data structure

Definition at line 739 of file heur_gcgrins.c.

References DEFAULT_COPYCUTS, DEFAULT_MAXNODES, DEFAULT_MINFIXINGRATE, DEFAULT_MINIMPROVE, DEFAULT_MINNODES, DEFAULT_NODESOFS, DEFAULT_NODESQUOT, DEFAULT_NWAITINGNODES, DEFAULT_USELPROWS, HEUR_DESC, HEUR_DISPCHAR, HEUR_FREQ, HEUR_FREQOFS, HEUR_MAXDEPTH, HEUR_NAME, HEUR_PRIORITY, HEUR_TIMING, and HEUR_USESSUBSCIP.

Referenced by SCIPincludeGcgPlugins().