Scippy

SCIP

Solving Constraint Integer Programs

Functions
heur_actconsdiving.h File Reference
Primal Heuristics

Detailed Description

LP diving heuristic that chooses fixings w.r.t. the active constraints the variable appear in.

Author
Tobias Achterberg

Diving heuristic: Iteratively fixes some fractional variable and resolves the LP-relaxation, thereby simulating a depth-first-search in the tree. Active Constraint Diving chooses a variable based on the active LP rows (equations are counted twice here). The variable score is calculated as a convex combination of the number of constraints the variable appears in, the sum of all positive coefficients and the absolute sum of all negative coefficients. The chosen variable is then rounded to the closest integer. One-level backtracking is applied: If the LP gets infeasible, the last fixings is undone, and the opposite fixing is tried. If this is infeasible, too, the procedure aborts.

Definition in file heur_actconsdiving.h.

#include "scip/scip.h"

Go to the source code of this file.

Functions

SCIP_RETCODE SCIPincludeHeurActconsdiving (SCIP *scip)
 

Function Documentation

SCIP_RETCODE SCIPincludeHeurActconsdiving ( SCIP *  scip)

creates the actconsdiving heuristic and includes it in SCIP

Parameters
scipSCIP data structure

Definition at line 338 of file heur_actconsdiving.c.

References DEFAULT_BACKTRACK, DEFAULT_LPRESOLVEDOMCHGQUOT, DEFAULT_LPSOLVEFREQ, DEFAULT_MAXDIVEAVGQUOT, DEFAULT_MAXDIVEAVGQUOTNOSOL, DEFAULT_MAXDIVEUBQUOT, DEFAULT_MAXDIVEUBQUOTNOSOL, DEFAULT_MAXLPITEROFS, DEFAULT_MAXLPITERQUOT, DEFAULT_MAXRELDEPTH, DEFAULT_MINRELDEPTH, DEFAULT_ONLYLPBRANCHCANDS, DIVESET_DIVETYPES, HEUR_DESC, HEUR_DISPCHAR, HEUR_FREQ, HEUR_FREQOFS, HEUR_MAXDEPTH, HEUR_NAME, HEUR_PRIORITY, HEUR_TIMING, HEUR_USESSUBSCIP, NULL, SCIP_CALL, SCIP_OKAY, SCIPallocMemory, SCIPcreateDiveset(), SCIPincludeHeurBasic(), SCIPsetHeurCopy(), SCIPsetHeurExit(), SCIPsetHeurFree(), and SCIPsetHeurInit().

Referenced by SCIPincludeDefaultPlugins().