# SCIP

Solving Constraint Integer Programs

type_prop.h File Reference

## Detailed Description

type definitions for propagators

Definition in file type_prop.h.

#include "scip/def.h"
#include "scip/type_retcode.h"
#include "scip/type_result.h"
#include "scip/type_scip.h"
#include "scip/type_timing.h"

Go to the source code of this file.

## Macros

#define SCIP_DECL_PROPCOPY(x)   SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop)

#define SCIP_DECL_PROPFREE(x)   SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop)

#define SCIP_DECL_PROPINIT(x)   SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop)

#define SCIP_DECL_PROPEXIT(x)   SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop)

#define SCIP_DECL_PROPINITPRE(x)   SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop)

#define SCIP_DECL_PROPEXITPRE(x)   SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop)

#define SCIP_DECL_PROPINITSOL(x)   SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop)

#define SCIP_DECL_PROPEXITSOL(x)   SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop, SCIP_Bool restart)

#define SCIP_DECL_PROPPRESOL(x)

#define SCIP_DECL_PROPEXEC(x)   SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop, SCIP_PROPTIMING proptiming, SCIP_RESULT* result)

#define SCIP_DECL_PROPRESPROP(x)

## Typedefs

typedef struct SCIP_Prop SCIP_PROP

typedef struct SCIP_PropData SCIP_PROPDATA

## ◆ SCIP_DECL_PROPCOPY

 #define SCIP_DECL_PROPCOPY ( x ) SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop)

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

input:

• scip : SCIP main data structure
• prop : the propagator itself

Definition at line 47 of file type_prop.h.

## ◆ SCIP_DECL_PROPFREE

 #define SCIP_DECL_PROPFREE ( x ) SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop)

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

input:

• scip : SCIP main data structure
• prop : the propagator itself

Definition at line 55 of file type_prop.h.

## ◆ SCIP_DECL_PROPINIT

 #define SCIP_DECL_PROPINIT ( x ) SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop)

initialization method of propagator (called after problem was transformed)

input:

• scip : SCIP main data structure
• prop : the propagator itself

Definition at line 63 of file type_prop.h.

## ◆ SCIP_DECL_PROPEXIT

 #define SCIP_DECL_PROPEXIT ( x ) SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop)

deinitialization method of propagator (called before transformed problem is freed)

input:

• scip : SCIP main data structure
• prop : the propagator itself

Definition at line 71 of file type_prop.h.

## ◆ SCIP_DECL_PROPINITPRE

 #define SCIP_DECL_PROPINITPRE ( x ) SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop)

presolving initialization method of propagator (called when presolving is about to begin)

This method is called when the presolving process is about to begin, even if presolving is turned off. The propagator may use this call to initialize its presolving data, before the presolving process begins.

Necessary modifications that have to be performed even if presolving is turned off should be done here or in the presolving deinitialization call (SCIP_DECL_PROPEXITPRE()).

input:

• scip : SCIP main data structure
• prop : the propagator itself

Definition at line 85 of file type_prop.h.

## ◆ SCIP_DECL_PROPEXITPRE

 #define SCIP_DECL_PROPEXITPRE ( x ) SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop)

presolving deinitialization method of propagator (called after presolving has been finished)

This method is called after the presolving has been finished, even if presolving is turned off. The propagator may use this call e.g. to clean up its presolving data.

Besides necessary modifications and clean up, no time consuming operations should be performed, especially if the problem has already been solved. Use the method SCIPgetStatus(), which in this case returns SCIP_STATUS_OPTIMAL, SCIP_STATUS_INFEASIBLE, SCIP_STATUS_UNBOUNDED, or SCIP_STATUS_INFORUNBD.

input:

• scip : SCIP main data structure
• prop : the propagator itself

Definition at line 100 of file type_prop.h.

## ◆ SCIP_DECL_PROPINITSOL

 #define SCIP_DECL_PROPINITSOL ( x ) SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop)

solving process initialization method of propagator (called when branch and bound process is about to begin)

This method is called when the presolving was finished and the branch and bound process is about to begin. The propagator may use this call to initialize its branch and bound specific data.

Besides necessary modifications and clean up, no time consuming operations should be performed, especially if the problem has already been solved. Use the method SCIPgetStatus(), which in this case returns SCIP_STATUS_OPTIMAL, SCIP_STATUS_INFEASIBLE, SCIP_STATUS_UNBOUNDED, or SCIP_STATUS_INFORUNBD.

input:

• scip : SCIP main data structure
• prop : the propagator itself

Definition at line 115 of file type_prop.h.

## ◆ SCIP_DECL_PROPEXITSOL

 #define SCIP_DECL_PROPEXITSOL ( x ) SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop, SCIP_Bool restart)

solving process deinitialization method of propagator (called before branch and bound process data is freed)

This method is called before the branch and bound process is freed. The propagator should use this call to clean up its branch and bound data.

input:

• scip : SCIP main data structure
• prop : the propagator itself
• restart : was this exit solve call triggered by a restart?

Definition at line 127 of file type_prop.h.

## ◆ SCIP_DECL_PROPPRESOL

 #define SCIP_DECL_PROPPRESOL ( x )
Value:
SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop, int nrounds, SCIP_PRESOLTIMING presoltiming, \
int nnewfixedvars, int nnewaggrvars, int nnewchgvartypes, int nnewchgbds, int nnewholes, \
int nnewdelconss, int nnewaddconss, int nnewupgdconss, int nnewchgcoefs, int nnewchgsides, \
int* nfixedvars, int* naggrvars, int* nchgvartypes, int* nchgbds, int* naddholes, \
int* ndelconss, int* naddconss, int* nupgdconss, int* nchgcoefs, int* nchgsides, SCIP_RESULT* result)
enum SCIP_Result SCIP_RESULT
Definition: type_result.h:52
enum SCIP_Retcode SCIP_RETCODE
Definition: type_retcode.h:53
SCIP_VAR ** x
Definition: circlepacking.c:54
unsigned int SCIP_PRESOLTIMING
Definition: type_timing.h:52

presolving method of propagator

The presolver should go through the variables and constraints and tighten the domains or constraints. Each tightening should increase the given total numbers of changes.

input:

• scip : SCIP main data structure
• prop : the propagator itself
• nrounds : number of presolving rounds already done
• presoltiming : current presolving timing
• nnewfixedvars : number of variables fixed since the last call to the presolving method
• nnewaggrvars : number of variables aggregated since the last call to the presolving method
• nnewchgvartypes : number of variable type changes since the last call to the presolving method
• nnewchgbds : number of variable bounds tightened since the last call to the presolving method
• nnewholes : number of domain holes added since the last call to the presolving method
• nnewdelconss : number of deleted constraints since the last call to the presolving method
• nnewaddconss : number of added constraints since the last call to the presolving method
• nnewupgdconss : number of upgraded constraints since the last call to the presolving method
• nnewchgcoefs : number of changed coefficients since the last call to the presolving method
• nnewchgsides : number of changed left or right hand sides since the last call to the presolving method
Note
the counters state the changes since the last call including the changes of this presolving method during its last call
if the propagator uses dual information for presolving it is nesassary to check via calling SCIPallowDualReds if dual reductions are allowed.

input/output:

• nfixedvars : pointer to total number of variables fixed of all presolvers
• naggrvars : pointer to total number of variables aggregated of all presolvers
• nchgvartypes : pointer to total number of variable type changes of all presolvers
• nchgbds : pointer to total number of variable bounds tightened of all presolvers
• naddholes : pointer to total number of domain holes added of all presolvers
• ndelconss : pointer to total number of deleted constraints of all presolvers
• naddconss : pointer to total number of added constraints of all presolvers
• nupgdconss : pointer to total number of upgraded constraints of all presolvers
• nchgcoefs : pointer to total number of changed coefficients of all presolvers
• nchgsides : pointer to total number of changed left/right hand sides of all presolvers

output:

• result : pointer to store the result of the presolving call

possible return values for *result:

• SCIP_UNBOUNDED : at least one variable is not bounded by any constraint in obj. direction -> problem is unbounded
• SCIP_CUTOFF : at least one constraint is infeasible in the variable's bounds -> problem is infeasible
• SCIP_SUCCESS : the presolving method found a reduction
• SCIP_DIDNOTFIND : the presolving method searched, but did not find a presolving change
• SCIP_DIDNOTRUN : the presolving method was skipped
• SCIP_DELAYED : the presolving method was skipped, but should be called again

Definition at line 179 of file type_prop.h.

## ◆ SCIP_DECL_PROPEXEC

 #define SCIP_DECL_PROPEXEC ( x ) SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop, SCIP_PROPTIMING proptiming, SCIP_RESULT* result)

execution method of propagator

Searches for domain propagations. The method is called in the node processing loop.

input:

• scip : SCIP main data structure
• prop : the propagator itself
• proptiming : current point in the node solving loop
• result : pointer to store the result of the propagation call

possible return values for *result:

• SCIP_CUTOFF : the current node is infeasible for the current domains
• SCIP_REDUCEDDOM : at least one domain reduction was found
• SCIP_DIDNOTFIND : the propagator searched, but did not find a domain reduction
• SCIP_DIDNOTRUN : the propagator was skipped
• SCIP_DELAYED : the propagator was skipped, but should be called again
• SCIP_DELAYNODE : the current node should be postponed (return value only valid for BEFORELP propagation)

Definition at line 203 of file type_prop.h.

## ◆ SCIP_DECL_PROPRESPROP

 #define SCIP_DECL_PROPRESPROP ( x )
Value:
SCIP_RETCODE x (SCIP* scip, SCIP_PROP* prop, SCIP_VAR* infervar, int inferinfo, \
SCIP_BOUNDTYPE boundtype, SCIP_BDCHGIDX* bdchgidx, SCIP_Real relaxedbd, SCIP_RESULT* result)
enum SCIP_Result SCIP_RESULT
Definition: type_result.h:52
enum SCIP_BoundType SCIP_BOUNDTYPE
Definition: type_lp.h:50
enum SCIP_Retcode SCIP_RETCODE
Definition: type_retcode.h:53
SCIP_VAR ** x
Definition: circlepacking.c:54
#define SCIP_Real
Definition: def.h:150

propagation conflict resolving method of propagator

This method is called during conflict analysis. If the propagator wants to support conflict analysis, it should call SCIPinferVarLbProp() or SCIPinferVarUbProp() in domain propagation instead of SCIPchgVarLb() or SCIPchgVarUb() in order to deduce bound changes on variables. In the SCIPinferVarLbProp() and SCIPinferVarUbProp() calls, the propagator provides a pointer to itself and an integer value "inferinfo" that can be arbitrarily chosen. The propagation conflict resolving method can then be implemented, to provide a "reasons" for the bound changes, i.e. the bounds of variables at the time of the propagation, that forced the propagator to set the conflict variable's bound to its current value. It can use the "inferinfo" tag to identify its own propagation rule and thus identify the "reason" bounds. The bounds that form the reason of the assignment must then be provided by calls to SCIPaddConflictLb(), SCIPaddConflictUb(), SCIPaddConflictBd(), SCIPaddConflictRelaxedLb(), SCIPaddConflictRelaxedUb(), SCIPaddConflictRelaxedBd(), and/or SCIPaddConflictBinvar() in the propagation conflict resolving method.

See the description of the propagation conflict resolving method of constraint handlers for further details.

Note
if the propagtor uses dual information it is nesassary to check via calling SCIPallowDualReds and SCIPallowObjProp if dual reductions and propgation with the current cutoff bound, resp., are allowed.

input:

• scip : SCIP main data structure
• prop : the propagator itself
• infervar : the conflict variable whose bound change has to be resolved
• inferinfo : the user information passed to the corresponding SCIPinferVarLbProp() or SCIPinferVarUbProp() call
• boundtype : the type of the changed bound (lower or upper bound)
• bdchgidx : the index of the bound change, representing the point of time where the change took place
• relaxedbd : the relaxed bound which is sufficient to be explained

output:

• result : pointer to store the result of the propagation conflict resolving call

possible return values for *result:

• SCIP_SUCCESS : the conflicting bound change has been successfully resolved by adding all reason bounds
• SCIP_DIDNOTFIND : the conflicting bound change could not be resolved and has to be put into the conflict set
Note
it is sufficient to explain/resolve the relaxed bound

Definition at line 244 of file type_prop.h.

## ◆ SCIP_PROP

 typedef struct SCIP_Prop SCIP_PROP

propagator

Definition at line 37 of file type_prop.h.

## ◆ SCIP_PROPDATA

 typedef struct SCIP_PropData SCIP_PROPDATA

locally defined propagator data

Definition at line 38 of file type_prop.h.