## Detailed Description

type definitions for presolvers

Definition in file type_presol.h.

`#include "scip/def.h"`

`#include "scip/type_retcode.h"`

`#include "scip/type_result.h"`

`#include "scip/type_scip.h"`

Go to the source code of this file.

## Macros | |

#define | SCIP_DECL_PRESOLCOPY(x) SCIP_RETCODE x (SCIP* scip, SCIP_PRESOL* presol) |

#define | SCIP_DECL_PRESOLFREE(x) SCIP_RETCODE x (SCIP* scip, SCIP_PRESOL* presol) |

#define | SCIP_DECL_PRESOLINIT(x) SCIP_RETCODE x (SCIP* scip, SCIP_PRESOL* presol) |

#define | SCIP_DECL_PRESOLEXIT(x) SCIP_RETCODE x (SCIP* scip, SCIP_PRESOL* presol) |

#define | SCIP_DECL_PRESOLINITPRE(x) SCIP_RETCODE x (SCIP* scip, SCIP_PRESOL* presol) |

#define | SCIP_DECL_PRESOLEXITPRE(x) SCIP_RETCODE x (SCIP* scip, SCIP_PRESOL* presol) |

#define | SCIP_DECL_PRESOLEXEC(x) |

## Typedefs | |

typedef struct SCIP_Presol | SCIP_PRESOL |

typedef struct SCIP_PresolData | SCIP_PRESOLDATA |

## Macro Definition Documentation

## ◆ SCIP_DECL_PRESOLCOPY

#define SCIP_DECL_PRESOLCOPY | ( | x | ) | SCIP_RETCODE x (SCIP* scip, SCIP_PRESOL* presol) |

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

input:

- scip : SCIP main data structure
- presol : the presolver itself

Definition at line 60 of file type_presol.h.

## ◆ SCIP_DECL_PRESOLFREE

#define SCIP_DECL_PRESOLFREE | ( | x | ) | SCIP_RETCODE x (SCIP* scip, SCIP_PRESOL* presol) |

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

input:

- scip : SCIP main data structure
- presol : the presolver itself

Definition at line 68 of file type_presol.h.

## ◆ SCIP_DECL_PRESOLINIT

#define SCIP_DECL_PRESOLINIT | ( | x | ) | SCIP_RETCODE x (SCIP* scip, SCIP_PRESOL* presol) |

initialization method of presolver (called after problem was transformed)

input:

- scip : SCIP main data structure
- presol : the presolver itself

Definition at line 76 of file type_presol.h.

## ◆ SCIP_DECL_PRESOLEXIT

#define SCIP_DECL_PRESOLEXIT | ( | x | ) | SCIP_RETCODE x (SCIP* scip, SCIP_PRESOL* presol) |

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

input:

- scip : SCIP main data structure
- presol : the presolver itself

Definition at line 84 of file type_presol.h.

## ◆ SCIP_DECL_PRESOLINITPRE

#define SCIP_DECL_PRESOLINITPRE | ( | x | ) | SCIP_RETCODE x (SCIP* scip, SCIP_PRESOL* presol) |

presolving initialization method of presolver (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 presolver may use this call to initialize its data structures.

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_PRESOLSEXITPRE()).

input:

- scip : SCIP main data structure
- presol : the presolver itself

Definition at line 98 of file type_presol.h.

## ◆ SCIP_DECL_PRESOLEXITPRE

#define SCIP_DECL_PRESOLEXITPRE | ( | x | ) | SCIP_RETCODE x (SCIP* scip, SCIP_PRESOL* presol) |

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

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

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

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
- presol : the presolver itself

Definition at line 116 of file type_presol.h.

## ◆ SCIP_DECL_PRESOLEXEC

#define SCIP_DECL_PRESOLEXEC | ( | x | ) |

**Value:**

**Definition:**objbenders.h:44

**Definition:**struct_presol.h:47

**Definition:**struct_scip.h:70

execution method of presolver

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
- presol : the presolver itself
- nrounds : number of presolving rounds already done
- presoltiming : current presolving timing
- nnewfixedvars : number of variables fixed since the last call to the presolver
- nnewaggrvars : number of variables aggregated since the last call to the presolver
- nnewchgvartypes : number of variable type changes since the last call to the presolver
- nnewchgbds : number of variable bounds tightened since the last call to the presolver
- nnewholes : number of domain holes added since the last call to the presolver
- nnewdelconss : number of deleted constraints since the last call to the presolver
- nnewaddconss : number of added constraints since the last call to the presolver
- nnewupgdconss : number of upgraded constraints since the last call to the presolver
- nnewchgcoefs : number of changed coefficients since the last call to the presolver
- nnewchgsides : number of changed left or right hand sides since the last call to the presolver

- Note
- the counters state the changes since the last call including the changes of this presolver during its last last call
- if the presolver uses dual information it is nesassary to check via calling SCIPallowWeakDualReds and SCIPallowStrongDualReds 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 presolver found a reduction
- SCIP_DIDNOTFIND : the presolver searched, but did not find a presolving change
- SCIP_DIDNOTRUN : the presolver was skipped

Definition at line 167 of file type_presol.h.

## Typedef Documentation

## ◆ SCIP_PRESOL

typedef struct SCIP_Presol SCIP_PRESOL |

presolver data structure

Definition at line 50 of file type_presol.h.

## ◆ SCIP_PRESOLDATA

typedef struct SCIP_PresolData SCIP_PRESOLDATA |

presolver specific data

Definition at line 51 of file type_presol.h.