reader_dec.c File Reference

Detailed Description

file reader for decompositions in the constraint based dec-file format.

Author

Gregor Hendel

This reader allows to read a file containing decompositions for constraints of the current original problem. The standard line ending for this format is '.dec'. The content of the file should obey the following format

\\ place for comments and statistics
NBLOCKS
2
BLOCK 0
consA
consB
[...]
BLOCK 1
consC
consD
[...]
MASTERCONSS
linkingcons

A block in a problem decomposition is a set of constraints that are independent from all other blocks after removing the special blocks of linking constraints denoted as MASTERCONSS.

Imagine the following example, which involves seven variables and the five constraints from the file above. The asterisks (*) indicate that the variable affects the feasibility of the constraint. In the special case of a linear optimization problem, the asterisks correspond to the nonzero entries of the constraint matrix.

                x1  x2  x3  x4  x5  x6  x7
       consA     *       *                 \ BLOCK 0
       consB     *   *                     /
       consC                 *   *         \ BLOCK 1
       consD                     *   *     /
linkingconss     *   *   *   *   *   *   * > MASTERCONSS

The nonzero pattern has been chosen in a way that after the removal of the last constraint 'linkingcons', the remaining problem consists of two independent parts, namely the blocks '0' and '1'.

The corresponding variable labels are inferred from the constraint labels. A variable is assigned the label

• of its unique block, if it only occurs in exactly 1 named block, and probably in MASTERCONSS.
• the special label of a linking variable if it occurs only in the master constraints or in 2 or even more named blocks.

Note

A trivial decomposition is to assign all constraints of a problem to the MASTERCONSS.

The number of blocks is the number of named blocks: a trivial decomposition should have 0 blocks

Definition in file reader_dec.c.

#include "scip/pub_dcmp.h"
#include "scip/pub_fileio.h"
#include "scip/pub_message.h"
#include "scip/pub_misc.h"
#include "scip/pub_reader.h"
#include "scip/pub_var.h"
#include "scip/reader_dec.h"
#include "scip/scip_dcmp.h"
#include "scip/scip_general.h"
#include "scip/scip_message.h"
#include "scip/scip_numerics.h"
#include "scip/scip_param.h"
#include "scip/scip_prob.h"
#include "scip/scip_reader.h"
#include "scip/scip_solve.h"
#include "scip/scip_var.h"
#include "scip/scip_mem.h"
#include "scip/type_dcmp.h"
#include <string.h>

Go to the source code of this file.

Macros
#define	READER_NAME   "decreader"
#define	READER_DESC   "file reader for constraint decompositions"
#define	READER_EXTENSION   "dec"

Typedefs
typedef enum Dec_Section	DEC_SECTION

Enumerations
enum	Dec_Section {   DEC_SECTION_INIT = 0 ,   DEC_SECTION_NBLOCKS = 1 ,   DEC_SECTION_BLOCK = 2 ,   DEC_SECTION_MASTER = 3 }

Functions
static SCIP_RETCODE	readDecomposition (SCIP *scip, const char *filename)
static	SCIP_DECL_READERCOPY (readerCopyDec)
static	SCIP_DECL_READERREAD (readerReadDec)
SCIP_RETCODE	SCIPincludeReaderDec (SCIP *scip)

Macro Definition Documentation

READER_NAME

#define READER_NAME   "decreader"

Definition at line 96 of file reader_dec.c.

READER_DESC

#define READER_DESC   "file reader for constraint decompositions"

Definition at line 97 of file reader_dec.c.

READER_EXTENSION

#define READER_EXTENSION   "dec"

Definition at line 98 of file reader_dec.c.

Typedef Documentation

DEC_SECTION

typedef enum Dec_Section DEC_SECTION

Definition at line 111 of file reader_dec.c.

Enumeration Type Documentation

Dec_Section

enum Dec_Section

Enumerator
DEC_SECTION_INIT	initial section before the number of blocks is specified
DEC_SECTION_NBLOCKS	section that contains the number of
DEC_SECTION_BLOCK
DEC_SECTION_MASTER

Definition at line 105 of file reader_dec.c.

Function Documentation

readDecomposition()

static SCIP_RETCODE readDecomposition ( SCIP *  scip, const char *  filename  )

static

reads the given decomposition file

Parameters

scip	SCIP data structure
filename	name of the input file

Definition at line 115 of file reader_dec.c.

References DEC_SECTION_BLOCK, DEC_SECTION_INIT, DEC_SECTION_MASTER, DEC_SECTION_NBLOCKS, FALSE, NULL, SCIP_Bool, SCIP_CALL, SCIP_CALL_TERMINATE, SCIP_DECOMP_LINKCONS, SCIP_MAXSTRLEN, SCIP_NOFILE, SCIP_OKAY, SCIP_READERROR, SCIP_STAGE_PROBLEM, SCIP_VERBLEVEL_NORMAL, SCIPaddDecomp(), SCIPallocBufferArray, SCIPcomputeDecompStats(), SCIPcomputeDecompVarsLabels(), SCIPcreateDecomp(), SCIPdebugMsg, SCIPdecompPrintStats(), SCIPdecompSetConsLabels(), SCIPerrorMessage, SCIPfclose(), SCIPfeof(), SCIPfgets(), SCIPfindCons(), SCIPfopen(), SCIPfreeBufferArray, SCIPgetBoolParam(), SCIPgetConss(), SCIPgetNConss(), SCIPgetStage(), SCIPprintSysError(), SCIPverbMessage(), SCIPwarningMessage(), and TRUE.

Referenced by SCIP_DECL_READERREAD().

SCIP_DECL_READERCOPY()

static SCIP_DECL_READERCOPY ( readerCopyDec  )

static

copy method for reader plugins (called when SCIP copies plugins)

Definition at line 342 of file reader_dec.c.

References NULL, READER_NAME, SCIP_CALL, SCIP_OKAY, SCIPincludeReaderDec(), and SCIPreaderGetName().

SCIP_DECL_READERREAD()

static SCIP_DECL_READERREAD ( readerReadDec  )

static

problem reading method of reader

Definition at line 356 of file reader_dec.c.

References NULL, readDecomposition(), READER_NAME, SCIP_CALL, SCIP_DIDNOTRUN, SCIP_OKAY, SCIP_READERROR, SCIP_STAGE_PROBLEM, SCIP_SUCCESS, SCIPerrorMessage, SCIPgetStage(), and SCIPreaderGetName().