net.sf.tweety.logics.pl.syntax

Class PropositionalFormula

java.lang.Object

net.sf.tweety.logics.pl.syntax.PropositionalFormula

All Implemented Interfaces:

net.sf.tweety.commons.Formula, net.sf.tweety.logics.commons.syntax.interfaces.ClassicalFormula, net.sf.tweety.logics.commons.syntax.interfaces.Conjuctable, net.sf.tweety.logics.commons.syntax.interfaces.Disjunctable, net.sf.tweety.logics.commons.syntax.interfaces.Invertable, net.sf.tweety.logics.commons.syntax.interfaces.ProbabilityAware, net.sf.tweety.logics.commons.syntax.interfaces.SimpleLogicalFormula

Direct Known Subclasses:

AssociativePropositionalFormula, Negation, Proposition, SpecialFormula

public abstract class PropositionalFormula
extends Object
implements net.sf.tweety.logics.commons.syntax.interfaces.ClassicalFormula

This class represents the common ancestor for propositional formulae.

Author:

Matthias Thimm, Tim Janus

Constructor Summary

Constructors

Constructor and Description
PropositionalFormula()

Method Summary

Modifier and Type	Method and Description
abstract PropositionalFormula	clone()
abstract PropositionalFormula	collapseAssociativeFormulas() This method collapses all associative operations appearing in this term, e.g.
Conjunction	combineWithAnd(net.sf.tweety.logics.commons.syntax.interfaces.Conjuctable f)
Disjunction	combineWithOr(net.sf.tweety.logics.commons.syntax.interfaces.Disjunctable f)
net.sf.tweety.logics.commons.syntax.interfaces.ClassicalFormula	complement()
abstract boolean	equals(Object other)
abstract Set<Proposition>	getAtoms()
abstract Set<PropositionalFormula>	getLiterals() Returns all literals, i.e.
Set<PossibleWorld>	getModels() Returns the set of models of this formula wrt.
abstract Set<PossibleWorld>	getModels(PropositionalSignature sig) Returns the set of models of this formula wrt.
Class<PropositionalPredicate>	getPredicateCls()
abstract Set<PropositionalPredicate>	getPredicates()
Collection<PropositionalFormula>	getPrimeImplicants() Returns the set of prime implicants of this formula.
PropositionalSignature	getSignature()
net.sf.tweety.math.probability.Probability	getUniformProbability() Returns this formula's probability in the uniform distribution.
abstract int	hashCode()
boolean	isConjunctiveClause() Checks whether this formula is a conjunctive clause, i.e.
boolean	isLiteral()
abstract int	numberOfOccurrences(Proposition p) Returns the number of occurrences of the given proposition within this formula
abstract PropositionalFormula	replace(Proposition p, PropositionalFormula f, int i) Replaces the ith instance of the proposition p by f.
boolean	resolvableWith(PropositionalFormula other) Checks whether this formula (which must be a conjunction of literals) is resolvable with the given formulas (which is also a conjunction of literals, i.e.
Conjunction	resolveWith(PropositionalFormula other) Resolves this formula with the given one (both have to be conjunctive clauses) and returns some resolvent.
PropositionalFormula	toBlakeCanonicalForm() This method returns this formula in Blake canonical form.
abstract Conjunction	toCnf() This method returns this formula in conjunctive normal form (CNF).
PropositionalFormula	toDnf() This method returns this formula in disjunctive normal form (DNF).
abstract PropositionalFormula	toNnf() This method returns this formula in negation normal form (NNF).
abstract PropositionalFormula	trim() Removes duplicates (identical formulas) from conjunctions and disjunctions and duplicate negations.

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PropositionalFormula

public PropositionalFormula()

Method Detail

getPredicateCls

public Class<PropositionalPredicate> getPredicateCls()

Specified by:

getPredicateCls in interface net.sf.tweety.logics.commons.syntax.interfaces.SimpleLogicalFormula

getSignature

public PropositionalSignature getSignature()

Specified by:

getSignature in interface net.sf.tweety.commons.Formula

getAtoms

public abstract Set<Proposition> getAtoms()

Specified by:

getAtoms in interface net.sf.tweety.logics.commons.syntax.interfaces.SimpleLogicalFormula

getLiterals

public abstract Set<PropositionalFormula> getLiterals()

Returns all literals, i.e. all formulas of the form "a" or "!a" where "a" is a proposition, that appear in this formula.

Returns:

all literals appearing in this formula.

combineWithAnd

public Conjunction combineWithAnd(net.sf.tweety.logics.commons.syntax.interfaces.Conjuctable f)

Specified by:

combineWithAnd in interface net.sf.tweety.logics.commons.syntax.interfaces.Conjuctable

combineWithOr

public Disjunction combineWithOr(net.sf.tweety.logics.commons.syntax.interfaces.Disjunctable f)

Specified by:

combineWithOr in interface net.sf.tweety.logics.commons.syntax.interfaces.Disjunctable

collapseAssociativeFormulas

public abstract PropositionalFormula collapseAssociativeFormulas()

This method collapses all associative operations appearing in this term, e.g. every a||(b||c) becomes a||b||c.

Returns:

the collapsed formula.

getPredicates

public abstract Set<PropositionalPredicate> getPredicates()

Specified by:

getPredicates in interface net.sf.tweety.logics.commons.syntax.interfaces.SimpleLogicalFormula

trim

public abstract PropositionalFormula trim()

Removes duplicates (identical formulas) from conjunctions and disjunctions and duplicate negations.

Returns:

an equivalent formula without duplicates.

getUniformProbability

public net.sf.tweety.math.probability.Probability getUniformProbability()

Returns this formula's probability in the uniform distribution.

Specified by:

getUniformProbability in interface net.sf.tweety.logics.commons.syntax.interfaces.ProbabilityAware

Returns:

this formula's probability in the uniform distribution.

toNnf

public abstract PropositionalFormula toNnf()

This method returns this formula in negation normal form (NNF). A formula is in NNF iff negations occur only directly in front of a proposition.

Returns:

the formula in NNF.

toCnf

public abstract Conjunction toCnf()

This method returns this formula in conjunctive normal form (CNF). A formula is in CNF iff it is a conjunction of disjunctions and in NNF.

Returns:

the formula in CNF.

toDnf

public PropositionalFormula toDnf()

This method returns this formula in disjunctive normal form (DNF). A formula is in DNF iff it is a disjunction of conjunctive clauses.

Returns:

the formula in DNF.

resolvableWith

public boolean resolvableWith(PropositionalFormula other)

Checks whether this formula (which must be a conjunction of literals) is resolvable with the given formulas (which is also a conjunction of literals, i.e. whether they contains exactly one complementary literal.

Parameters:

other - a conjunction of literals

Returns:

"true" iff this formula is resolvable with the other formula.

resolveWith

public Conjunction resolveWith(PropositionalFormula other)

Resolves this formula with the given one (both have to be conjunctive clauses) and returns some resolvent.

Parameters:

other - a conjunction of formulas

Returns:

some resolvent.

toBlakeCanonicalForm

public PropositionalFormula toBlakeCanonicalForm()

This method returns this formula in Blake canonical form. A formula is in Blake canonical form iff it is the disjunction of its prime implicants.

Returns:

the formula in Blake canonical form

getPrimeImplicants

public Collection<PropositionalFormula> getPrimeImplicants()

Returns the set of prime implicants of this formula.

Returns:

the set of prime implicants of this formula.

getModels

public Set<PossibleWorld> getModels()

Returns the set of models of this formula wrt. a signature that only contains the propositions appearing in this formula.

Returns:

the set of models of this formula wrt. a signature that only contains the propositions appearing in this formula.

getModels

public abstract Set<PossibleWorld> getModels(PropositionalSignature sig)

Returns the set of models of this formula wrt. the given signature.

Parameters:

sig - some propositional signature

Returns:

the set of models of this formula wrt. the given signature.

complement

public net.sf.tweety.logics.commons.syntax.interfaces.ClassicalFormula complement()

Specified by:

complement in interface net.sf.tweety.logics.commons.syntax.interfaces.Invertable

isConjunctiveClause

public boolean isConjunctiveClause()

Checks whether this formula is a conjunctive clause, i.e. whether it is a conjunction of literals.

Returns:

"true" iff this formula is a conjunctive clause.

numberOfOccurrences

public abstract int numberOfOccurrences(Proposition p)

Returns the number of occurrences of the given proposition within this formula

Parameters:

p - some proposition

Returns:

the number of occurrences of the given proposition within this formula

replace

public abstract PropositionalFormula replace(Proposition p,
                                             PropositionalFormula f,
                                             int i)

Replaces the ith instance of the proposition p by f.

Parameters:

p - some proposition

f - some formula

i - the index of the proposition

Returns:

a new formula with the ith instance of the proposition p replaced by f.

isLiteral

public boolean isLiteral()

Specified by:

isLiteral in interface net.sf.tweety.logics.commons.syntax.interfaces.SimpleLogicalFormula

equals

public abstract boolean equals(Object other)

Specified by:

equals in interface net.sf.tweety.logics.commons.syntax.interfaces.SimpleLogicalFormula

Overrides:

equals in class Object

hashCode

public abstract int hashCode()

Specified by:

hashCode in interface net.sf.tweety.logics.commons.syntax.interfaces.SimpleLogicalFormula

Overrides:

hashCode in class Object

clone

public abstract PropositionalFormula clone()

Specified by:

clone in interface net.sf.tweety.logics.commons.syntax.interfaces.SimpleLogicalFormula

Overrides:

clone in class Object