AbcCutGenerator Class Reference

Interface between Abc and Cut Generation Library. More...

#include <AbcCutGenerator.h>

Collaboration diagram for AbcCutGenerator:

Public Member Functions
Generate Cuts

bool	generateCuts (OsiCuts &cs, bool fullScan)
	Generate cuts for the client model.
Constructors and destructors

	AbcCutGenerator ()
	Default constructor.
	AbcCutGenerator (AbcModel model, CglCutGenerator generator, int howOften=1, const char *name=NULL, bool normal=true, bool atSolution=false, bool infeasible=false)
	Normal constructor.
	AbcCutGenerator (const AbcCutGenerator &)
	Copy constructor.
AbcCutGenerator &	operator= (const AbcCutGenerator &rhs)
	Assignment operator.
	~AbcCutGenerator ()
	Destructor.
Gets and sets

void	refreshModel (AbcModel *model)
	Set the client model.
const char *	cutGeneratorName () const
	return name of generator
void	setHowOften (int value)
	Set the cut generation interval.
int	howOften () const
	Get the cut generation interval.
bool	normal () const
	Get whether the cut generator should be called in the normal place.
void	setNormal (bool value)
	Set whether the cut generator should be called in the normal place.
bool	atSolution () const
	Get whether the cut generator should be called when a solution is found.
void	setAtSolution (bool value)
	Set whether the cut generator should be called when a solution is found.
bool	whenInfeasible () const
	Get whether the cut generator should be called when the subproblem is found to be infeasible.
void	setWhenInfeasible (bool value)
	Set whether the cut generator should be called when the subproblem is found to be infeasible.
CglCutGenerator *	generator () const
	Get the `CglCutGenerator` bound to this `AbcCutGenerator`.
Private Attributes
AbcModel *	model_
	The client model.
CglCutGenerator *	generator_
int	whenCutGenerator_
	Number of nodes between calls to the CglCutGenerator::generateCuts routine.
char *	generatorName_
	Name of generator.
bool	normal_
	Whether to call the generator in the normal place.
bool	atSolution_
	Whether to call the generator when a new solution is found.
bool	whenInfeasible_
	Whether to call generator when a subproblem is found to be infeasible.

Detailed Description

Interface between Abc and Cut Generation Library.

AbcCutGenerator is intended to provide an intelligent interface between Abc and the cutting plane algorithms in the CGL. A AbcCutGenerator is bound to a CglCutGenerator and to an AbcModel. It contains parameters which control when and how the generateCuts method of the CglCutGenerator will be called.

The builtin decision criteria available to use when deciding whether to generate cuts are limited: every X nodes, when a solution is found, and when a subproblem is found to be infeasible. The idea is that the class will grow more intelligent with time.

Todo:: Add a pointer to function member which will allow a client to install their own decision algorithm to decide whether or not to call the CGL generateCuts method. Create a default decision method that looks at the builtin criteria.

Todo:: It strikes me as not good that generateCuts contains code specific to individual CGL algorithms. Another set of pointer to function members, so that the client can specify the cut generation method as well as pre- and post-generation methods? Taken a bit further, should this class contain a bunch of pointer to function members, one for each of the places where the cut generator might be referenced? Initialization, root node, search tree node, discovery of solution, and termination all come to mind. Initialization and termination would also be useful for instrumenting sbb.

Definition at line 69 of file AbcCutGenerator.h.

Constructor & Destructor Documentation

AbcCutGenerator::AbcCutGenerator ( )

Default constructor.

AbcCutGenerator::AbcCutGenerator	(	AbcModel *	model,
		CglCutGenerator *	generator,
		int	howOften = `1`,
		const char *	name = `NULL`,
		bool	normal = `true`,
		bool	atSolution = `false`,
		bool	infeasible = `false`
	)

Normal constructor.

AbcCutGenerator::AbcCutGenerator ( const AbcCutGenerator & )

Copy constructor.

AbcCutGenerator::~AbcCutGenerator ( )

Destructor.

Member Function Documentation

bool AbcCutGenerator::generateCuts	(	OsiCuts &	cs,
		bool	fullScan
	)

Generate cuts for the client model.

Evaluate the state of the client model and decide whether to generate cuts. The generated cuts are inserted into and returned in the collection of cuts cs.

If fullScan is true, the generator is obliged to call the CGL generateCuts routine. Otherwise, it is free to make a local decision. The current implementation uses whenCutGenerator_ to decide.

The routine returns true if reoptimisation is needed (because the state of the solver interface has been modified).

AbcCutGenerator& AbcCutGenerator::operator= ( const AbcCutGenerator & rhs )

Assignment operator.

void AbcCutGenerator::refreshModel ( AbcModel * model )

Set the client model.

In addition to setting the client model, refreshModel also calls the refreshSolver method of the CglCutGenerator object.

const char* AbcCutGenerator::cutGeneratorName ( ) const [inline]

return name of generator

Definition at line 124 of file AbcCutGenerator.h.

void AbcCutGenerator::setHowOften ( int value )

Set the cut generation interval.

Set the number of nodes evaluated between calls to the Cgl object's generateCuts routine.

If value is positive, cuts will always be generated at the specified interval. If value is negative, cuts will initially be generated at the specified interval, but Abc may adjust the value depending on the success of cuts produced by this generator.

A value of -100 disables the generator, while a value of -99 means just at root.

int AbcCutGenerator::howOften ( ) const [inline]

Get the cut generation interval.

Definition at line 146 of file AbcCutGenerator.h.

bool AbcCutGenerator::normal ( ) const [inline]

Get whether the cut generator should be called in the normal place.

Definition at line 150 of file AbcCutGenerator.h.

void AbcCutGenerator::setNormal ( bool value ) [inline]

Set whether the cut generator should be called in the normal place.

Definition at line 153 of file AbcCutGenerator.h.

bool AbcCutGenerator::atSolution ( ) const [inline]

Get whether the cut generator should be called when a solution is found.