net.sf.tweety.lp.asp.syntax

Class DefaultNegation

java.lang.Object

net.sf.tweety.lp.asp.syntax.ASPElement

net.sf.tweety.lp.asp.syntax.ASPBodyElement

net.sf.tweety.lp.asp.syntax.DefaultNegation

All Implemented Interfaces:

net.sf.tweety.commons.Formula, net.sf.tweety.logics.commons.syntax.interfaces.ComplexLogicalFormula, net.sf.tweety.logics.commons.syntax.interfaces.LogicStructure, net.sf.tweety.logics.commons.syntax.interfaces.SimpleLogicalFormula

public class DefaultNegation
extends ASPBodyElement

This class represents a default negated literal, i.e. "not a", where a is a classical atom or an aggregate atom.

In answer set programming, the body of a rule is usually composed of a set of positive and negative literals, where this valuation refers to default negation or negation as failure. When implementing a rule, there are two opportunities:

• implement the rule with two distinct lists, representing the sets of positive and negative literals
• implement the rule with one set containing super literals, where a super literal can be positive or strictly negated, with or without default negation.

This library takes the second approach, which allows more flexibility, but comes at the cost that malformed constructs like "not not a" are not intercepted by the library.

Author:

Tim Janus, Thomas Vengels, Anna Gessler

Constructor Summary

Constructors

Constructor and Description
DefaultNegation(ASPBodyElement at) Creates new default negation with the given literal.

Method Summary

Modifier and Type	Method and Description
DefaultNegation	clone()
boolean	equals(Object obj)
Set<ASPAtom>	getAtoms()
ASPBodyElement	getLiteral()
SortedSet<ASPLiteral>	getLiterals() Returns all literals in this element in form of a SortedSet.
Set<net.sf.tweety.logics.commons.syntax.Predicate>	getPredicates()
net.sf.tweety.logics.fol.syntax.FolSignature	getSignature()
Set<net.sf.tweety.logics.commons.syntax.interfaces.Term<?>>	getTerms()
<C extends net.sf.tweety.logics.commons.syntax.interfaces.Term<?>> Set<C>	getTerms(Class<C> cls)
int	hashCode()
boolean	isLiteral()
boolean	isWellFormed()
void	setLiteral(ASPBodyElement literal)
ASPBodyElement	substitute(net.sf.tweety.logics.commons.syntax.interfaces.Term<?> t, net.sf.tweety.logics.commons.syntax.interfaces.Term<?> v)
String	toString()

Methods inherited from class net.sf.tweety.lp.asp.syntax.ASPElement

containsTermsOfType, exchange, getPredicateCls, isGround, substitute

Methods inherited from class java.lang.Object

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

Constructor Detail

DefaultNegation

public DefaultNegation(ASPBodyElement at)

Creates new default negation with the given literal.

Parameters:

at - a classical atom or an aggregate atom

Method Detail

toString

public String toString()

Overrides:

toString in class Object

getLiterals

public SortedSet<ASPLiteral> getLiterals()

Description copied from class: ASPBodyElement

Returns all literals in this element in form of a SortedSet. Literals are atoms or strict negations of atoms.

Specified by:

getLiterals in class ASPBodyElement

Returns:

all the literals used in the rule element

getPredicates

public Set<net.sf.tweety.logics.commons.syntax.Predicate> getPredicates()

Specified by:

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

Specified by:

getPredicates in class ASPElement

getAtoms

public Set<ASPAtom> getAtoms()

Specified by:

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

Specified by:

getAtoms in class ASPElement

substitute

public ASPBodyElement substitute(net.sf.tweety.logics.commons.syntax.interfaces.Term<?> t,
                                 net.sf.tweety.logics.commons.syntax.interfaces.Term<?> v)

Specified by:

substitute in interface net.sf.tweety.logics.commons.syntax.interfaces.ComplexLogicalFormula

Specified by:

substitute in class ASPBodyElement

getSignature

public net.sf.tweety.logics.fol.syntax.FolSignature getSignature()

Specified by:

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

Specified by:

getSignature in class ASPElement

isWellFormed

public boolean isWellFormed()

Specified by:

isWellFormed in interface net.sf.tweety.logics.commons.syntax.interfaces.ComplexLogicalFormula

Overrides:

isWellFormed in class ASPElement

isLiteral

public boolean isLiteral()

getTerms

public Set<net.sf.tweety.logics.commons.syntax.interfaces.Term<?>> getTerms()

getTerms

public <C extends net.sf.tweety.logics.commons.syntax.interfaces.Term<?>> Set<C> getTerms(Class<C> cls)

clone

public DefaultNegation clone()

Specified by:

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

Specified by:

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

Specified by:

clone in class ASPElement

getLiteral

public ASPBodyElement getLiteral()

setLiteral

public void setLiteral(ASPBodyElement literal)

hashCode

public int hashCode()

Specified by:

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

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Specified by:

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

Overrides:

equals in class Object