Package org.tweetyproject.logics.pl.syntax

Class Proposition

java.lang.Object

org.tweetyproject.logics.pl.syntax.PlFormula

org.tweetyproject.logics.pl.syntax.Proposition

All Implemented Interfaces:

Comparable<Proposition>, Formula, Atom, ClassicalFormula, Conjunctable, Disjunctable, Invertable, ProbabilityAware, SimpleLogicalFormula

Direct Known Subclasses:

QueryProposition

public class Proposition
extends PlFormula
implements Atom, Comparable<Proposition>

This class represents a simple proposition in propositional logic.

Author:

Matthias Thimm, Tim Janus

Nested Class Summary

Nested classes/interfaces inherited from interface org.tweetyproject.logics.commons.syntax.interfaces.Atom

Atom.AtomImpl, Atom.RETURN_SET_PREDICATE

Constructor Summary

Constructors

Constructor	Description
Proposition()	Default-Ctor for dynamic instantiation
Proposition(String name)	Creates a new proposition of the given name.
Proposition(Proposition other)	constructor

Method Summary

Modifier and Type	Method	Description
void	addArgument(Term<?> arg)	Adds an argument to the atom's argument list
Proposition	clone()	Creates a deep copy of this formula
PlFormula	collapseAssociativeFormulas()	This method collapses all associative operations appearing in this term, e.g.
int	compareTo(Proposition o)
boolean	equals(Object obj)
List<? extends Term<?>>	getArguments()
Set<Proposition>	getAtoms()	Processes the set of all atoms which appear in this formula
Set<PlFormula>	getLiterals()	Returns all literals, i.e.
Set<PossibleWorld>	getModels(PlSignature sig)	Returns the set of models of this formula wrt.
String	getName()
PlPredicate	getPredicate()
Set<PlPredicate>	getPredicates()	Processes the set of all predicates which appear in this formula
PlSignature	getSignature()	Returns the signature of the language of this formula.
int	hashCode()
boolean	isComplete()
boolean	isLiteral()
int	numberOfOccurrences(Proposition p)	Returns the number of occurrences of the given proposition within this formula
PlFormula	replace(Proposition p, PlFormula f, int i)	Replaces the ith instance of the proposition p by f.
Atom.RETURN_SET_PREDICATE	setPredicate(Predicate predicate)	Changes the predicate of the atom.
Conjunction	toCnf()	This method returns this formula in conjunctive normal form (CNF).
PlFormula	toNnf()	This method returns this formula in negation normal form (NNF).
String	toString()
PlFormula	trim()	Removes duplicates (identical formulas) from conjunctions and disjunctions and removes duplicate negations.

Methods inherited from class org.tweetyproject.logics.pl.syntax.PlFormula

combineWithAnd, combineWithOr, complement, getModels, getPredicateCls, getPrimeImplicants, getUniformProbability, isClause, isConjunctiveClause, resolvableWith, resolveWith, toBlakeCanonicalForm, toDnf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.tweetyproject.logics.commons.syntax.interfaces.SimpleLogicalFormula

getPredicateCls

Constructor Details

Proposition

public Proposition()

Default-Ctor for dynamic instantiation

Proposition

public Proposition(String name)

Creates a new proposition of the given name.

Parameters:

name - the name of the proposition.

Proposition

public Proposition(Proposition other)

constructor

Parameters:

other - another proposition

Method Details

getName

public String getName()

Specified by:

getName in interface Atom

Returns:

the name of this proposition.

getPredicate

public PlPredicate getPredicate()

Specified by:

getPredicate in interface Atom

Returns:

the predicate of the atom

getPredicates

public Set<PlPredicate> getPredicates()

Description copied from interface: SimpleLogicalFormula

Processes the set of all predicates which appear in this formula

Specified by:

getPredicates in interface SimpleLogicalFormula

Specified by:

getPredicates in class PlFormula

Returns:

all predicates that appear in this formula

toString

public String toString()

Overrides:

toString in class Object

collapseAssociativeFormulas

public PlFormula collapseAssociativeFormulas()

Description copied from class: PlFormula

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

Specified by:

collapseAssociativeFormulas in class PlFormula

Returns:

the collapsed formula.

getSignature

public PlSignature getSignature()

Description copied from interface: Formula

Returns the signature of the language of this formula.

Specified by:

getSignature in interface Formula

Overrides:

getSignature in class PlFormula

Returns:

the signature of the language of this formula.

hashCode

public int hashCode()

Specified by:

hashCode in interface SimpleLogicalFormula

Specified by:

hashCode in class PlFormula

equals

public boolean equals(Object obj)

Specified by:

equals in interface SimpleLogicalFormula

Specified by:

equals in class PlFormula

toNnf

public PlFormula toNnf()

Description copied from class: PlFormula

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.

Specified by:

toNnf in class PlFormula

Returns:

the formula in NNF.

clone

public Proposition clone()

Description copied from interface: SimpleLogicalFormula

Creates a deep copy of this formula

Specified by:

clone in interface SimpleLogicalFormula

Specified by:

clone in class PlFormula

Returns:

the cloned formula

trim

public PlFormula trim()

Description copied from class: PlFormula

Removes duplicates (identical formulas) from conjunctions and disjunctions and removes duplicate negations. Simplifies equivalences and implications with equivalent formulas (A=>A, A<=>A) to tautologies.

Specified by:

trim in class PlFormula

Returns:

an equivalent formula without duplicates.

addArgument

public void addArgument(Term<?> arg)

Description copied from interface: Atom

Adds an argument to the atom's argument list

Specified by:

addArgument in interface Atom

Parameters:

arg - The next argument

getArguments

public List<? extends Term<?>> getArguments()

Specified by:

getArguments in interface Atom

Returns:

A list containing all the arguments of this specific atom

isComplete

public boolean isComplete()

Specified by:

isComplete in interface Atom

Returns:

true if the size of the argument list is equal to the arity of the predicate

getAtoms

public Set<Proposition> getAtoms()

Description copied from interface: SimpleLogicalFormula

Processes the set of all atoms which appear in this formula

Specified by:

getAtoms in interface SimpleLogicalFormula

Specified by:

getAtoms in class PlFormula

Returns:

The set of all atoms

isLiteral

public boolean isLiteral()

Specified by:

isLiteral in interface SimpleLogicalFormula

Overrides:

isLiteral in class PlFormula

Returns:

true if the formula represents a literal in the language or false otherwise

getLiterals

public Set<PlFormula> getLiterals()

Description copied from class: PlFormula

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

Specified by:

getLiterals in class PlFormula

Returns:

all literals appearing in this formula.

setPredicate

public Atom.RETURN_SET_PREDICATE setPredicate(Predicate predicate)

Description copied from interface: Atom

Changes the predicate of the atom. Given an old Predicate po and a new predicate pn with their list of arguments types at(po) and at(pn) and the arguments of this Atom: arg(this) this method distinguishes between three cases: 1. The predicate only differ in the names, returning RSP_SUCCESS 2. The old predicates argument types is a sub-list of the new argument types then the method returns RSP_INCOMPLETE and the atoms isComplete() method returns false 3. The new predicates argument types is a sub-list of the old argument types then the method returns RSP_TRUNCATED and the arguments of this atom are truncated too and isComplete() returns true. 4. The old and new predicates' argument types differ then the list of arguments of the atom get cleared and isComplete() returns false.

Specified by:

setPredicate in interface Atom

Parameters:

predicate - some predicate

Returns:

Depends on the cases described above: 1. RSP_SUCCESS 2. RSP_INCOMPLETE 3. RSP_TRUNCATED 4. RSP_CLEARED

compareTo

public int compareTo(Proposition o)

Specified by:

compareTo in interface Comparable<Proposition>

toCnf

public Conjunction toCnf()

Description copied from class: PlFormula

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. The CNF generated by this method is not necessarily minimal.

Specified by:

toCnf in class PlFormula

Returns:

the formula in CNF.

numberOfOccurrences

public int numberOfOccurrences(Proposition p)

Description copied from class: PlFormula

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

Specified by:

numberOfOccurrences in class PlFormula

Parameters:

p - some proposition

Returns:

the number of occurrences of the given proposition within this formula

replace

public PlFormula replace(Proposition p,
 PlFormula f,
 int i)

Description copied from class: PlFormula

Replaces the ith instance of the proposition p by f.

Specified by:

replace in class PlFormula

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.

getModels

public Set<PossibleWorld> getModels(PlSignature sig)

Description copied from class: PlFormula

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

Specified by:

getModels in class PlFormula

Parameters:

sig - some propositional signature

Returns:

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