Constraint Class Reference

The constraint used by the compact representation. More...

#include <Queens.h>

Inheritance diagram for Constraint:

List of all members.

Public Types
typedef FastVector< Variable * >::const_iterator	variable_iterator
Public Member Functions
	Constraint (int queens=0)
virtual bool	check () const
	Constraint (Problem &problem)
	Constraint (Problem &problem, const Constraint &constraint)
double	weight () const
double	weight (const Variable &variable, const Value &value) const
double	minWeight () const
double	maxWeight () const
void	buildWrapper (const wstring &model, size_t nPairs, double probability, bool flawed)
void	buildEmpty ()
	Prepare an empty constraint (i.e. no allowed values).
void	addPair (int value0, int value1)
	Add a pair of allowed values to a constraint.
virtual bool	check () const
bool	isFlawless () const
ulonglong	allowedTuples () const
	Return the number of tuples allowed by the constraint.
virtual wostream &	print (wostream &wos) const
	Constraint ()
virtual	~Constraint ()
	Destructor.
variable_iterator	add (Variable &variable)
	Add `variable' to the list of variables in this constraint.
void	remove (Variable &variable, bool recursive=false)
	Remove `variable' from the list of variables in this constraint.
void	setId (id_t id)
	Set the constraint's id.
id_t	id () const
	Return the constraint's id.
virtual wstring	name () const
virtual wstring	color () const
virtual wstring	textColor () const
bool	isActive () const
void	activate ()
	Activate the constraint.
void	deactivate ()
	Deactivate the constraint.
bool	isComplete () const
bool	involves (const Variable &variable) const
Variable &	pair (const Variable &variable) const
size_t	variables () const
size_t	order () const
	Same as `variables()'. Return the order of the constraint.
const variable_iterator	beginVariables () const
	Return an iterator to the first variable in this constraint.
const variable_iterator	endVariables () const
	Return an interator past the last variable in this constraint.
const variable_iterator	secondVariable () const
Variable &	findVariable (bool instantiated=false) const
bool	isSatisfied () const
virtual bool	check () const =0
virtual bool	propagate (Variable &)
bool	tryOut (Variable &variable0, Value &value0, Variable &variable1, Value &value1) const
virtual ulonglong	validTuples () const
ulonglong	maxTuples () const
long double	tightness () const
bool	isLoose () const
virtual ulonglong	invalidTuples () const
ulonglong	checks () const
	Return the number of constraint checks for this constraint.
ulonglong	failures () const
	Return the number of constraint check failures for this constraint.
virtual void	init ()
virtual void	done ()
	Cleanup. Make sure you call this from derived classes.
size_t	instantiatedVariables () const
size_t	uninstantiatedVariables () const
void	inc ()
	Increment the number of instantiated variables.
void	dec ()
	Decrement the number of instantiated variables.
void	incrementWeight ()
	Increment the constraint's weight.
ulonglong	weight () const
	Return the constraint's weight.
virtual wostream &	print (wostream &wos) const
Friends
CSP_API wostream &	operator<< (wostream &wos, const Constraint &constraint)
	The constraint's output operator.

---

Detailed Description

The constraint used by the compact representation.

Abstract super class for defining CSP constraints.

---

Constructor & Destructor Documentation

Constraint::Constraint (   )

Create a new constraint object.

---

Member Function Documentation

virtual bool Constraint::check (   )  const [virtual]

Return `true' if the constraint is satisfied by the current assignment.

virtual wstring Constraint::color (   )  const [inline, virtual]

Return the constraint's drawing color, if the derived class decided to assign it one. The default color is "black". Returns: the constraint's color.

Variable & Constraint::findVariable (  bool  instantiated = false  )  const

Return the first instantiated/uninstantiated variable in the constraint. At least one such variable should exist at the time of the call. Parameters: instantiated  `false' if looking for uninstantiated variables, `true' if looking for instantiated variables. Returns: the first matching variable.

virtual void Constraint::init (   )  [inline, virtual]

This performs a few initializations that are required before starting a new search. Make sure you call this from derived classes.

size_t Constraint::instantiatedVariables (   )  const [inline]

Return the number of instantiated variables involved in this constraint.

virtual ulonglong Constraint::invalidTuples (   )  const [inline, virtual]

Return the number of tuples disallowed by the constraint.

bool Constraint::involves (  const Variable &  variable  )  const [inline]

Return `true' if this constraint involves the given variable, `false' otherwise. Parameters: variable  the variable to be found in the list of variables involved in this constraint. Returns: return `true' if the given variable is found, `false' otherwise.

bool Constraint::isActive (   )  const [inline]

Return the constraint's active status. Returns: `true' if the constraint is active, `false' otherwise.

bool Constraint::isComplete (   )  const [inline]

A constraint is considered `complete' if all the variables involved have been instantiated. Returns: `true' if the constraint is `complete'.

bool Constraint::isFlawless (   )  const

Return `true' if every value in the variables involved in this constraint has a support in the other variable.

bool Constraint::isLoose (   )  const

Return `true' if the constraint's tightness is 0 (i.e. all tuples are valid), `false' otherwise.

bool Constraint::isSatisfied (   )  const [inline]

Check whether or not the constraint is satisfied by the current assignments of its variables and update the constraint check counters. The implementation should work if the variables involved have had their domain reduced to a single value, regardless of wether they have been instantiated or not. Calling this method is the proper way of verifying that a constraint is satisfied. Returns: `true' if the constraint is satisfied, `false' otherwise.

ulonglong Constraint::maxTuples (   )  const

Return the maximum number of tuples allowed by the constraint, which is the product of the domain sizes of all the variables involved in the constraint.

wstring Constraint::name (   )  const [virtual]

Return the constraint's name, if the derived class decided to assign it one. The default is to return the constraint's id as a string. Returns: the constraint's name.

Variable& Constraint::pair (  const Variable &  variable  )  const [inline]

Given one variable involved in this (assumed binary) constraint, this method will return the other variable (the pair). Parameters: variable  one of the variables involved in the constraint. Returns: the other variable involved in the constraint.

virtual wostream& Constraint::print (  wostream &  wos  )  const [virtual]

Print the constraint at the given stream. Parameters: wos  the output stream to print to. Returns: the given stream.

virtual bool Constraint::propagate (  Variable &   )  [inline, virtual]

Propagate this constraint. If you decide to overwrite this function, you can prune domains of other variables, provided that you make correct use of [save|restore|postpone|add]Diffs. This should work regardles of the arity of the constraint. Parameters: modifiedVariable  the variable that has been modified; obviously this should be involved in the current constraint. Returns: `true' if the propagation was successful, `false' otherwise. Reimplemented in AllDiff.

const variable_iterator Constraint::secondVariable (   )  const [inline]

This is for convenience only, since binary constraints are so common. Use this for binary constraints only! Returns: an iterator pointing to the second variable in this constraint.

virtual wstring Constraint::textColor (   )  const [inline, virtual]

Return the constraint's text color, if the derived class decided to assign it one. The default color is "black". Returns: the constraint's text color.

long double Constraint::tightness (   )  const [inline]

Return the constraint's tightness, i.e. 1-validTuples()/maxTuples().

bool Constraint::tryOut (  Variable &  variable0, Value &  value0, Variable &  variable1, Value &  value1 )  const

Check if the constraint is satisfied by the assignment of `value0' to `variable0' and `value1' to `variable1'.

size_t Constraint::uninstantiatedVariables (   )  const [inline]

Return the number of uninstantiated variables involved in this constraint.

ulonglong Constraint::validTuples (   )  const [virtual]

Return the number of tuples allowed by the constraint.

size_t Constraint::variables (   )  const [inline]

Return the number of variables involved in the constraint. Returns: the number of variables involved in the constraint.

---

The documentation for this class was generated from the following files:

• Queens.h
• examples/Random.h
• Constraint.h
• Queens.cc
• examples/Random.cc
• Constraint.cc

---