Package org.tweetyproject.lp.asp.syntax

Class DefaultNegation

java.lang.Object

org.tweetyproject.lp.asp.syntax.ASPElement

org.tweetyproject.lp.asp.syntax.ASPBodyElement

org.tweetyproject.lp.asp.syntax.DefaultNegation

All Implemented Interfaces:

Formula, ComplexLogicalFormula, LogicStructure, 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.

Note: 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 options:

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

Method Summary

Modifier and Type	Method	Description
DefaultNegation	clone()	Creates a deep copy of this formula
boolean	equals(Object obj)
Set<ASPAtom>	getAtoms()	Processes the set of all atoms which appear in this formula
ASPBodyElement	getLiteral()	Return the default negated literal
SortedSet<ASPLiteral>	getLiterals()	Returns all literals in this element in form of a SortedSet.
Set<Predicate>	getPredicates()	Processes the set of all predicates which appear in this formula
FolSignature	getSignature()	Returns the signature of the language of this formula.
Set<Term<?>>	getTerms()
<C extends Term<?>> Set<C>	getTerms(Class<C> cls)	Processes the set containing all terms of type C.
int	hashCode()
boolean	isLiteral()
boolean	isWellFormed()	Checks if this formula is well formed in the logical langauge.
String	printToClingo()	Returns a representation of this ASP element in clingo (potassco) syntax.
String	printToDLV()	Returns a representation of this ASP element in DLV syntax.
void	setLiteral(ASPBodyElement literal)	Set the default negated literal.
ASPBodyElement	substitute(Term<?> t, Term<?> v)	Substitutes all occurrences of term "v" in this formula by term "t" and returns the new formula.
String	toString()

Methods inherited from class org.tweetyproject.lp.asp.syntax.ASPElement

containsTermsOfType, exchange, getPredicateCls, isGround, substitute

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Details

DefaultNegation

public DefaultNegation()

Constructor

DefaultNegation

public DefaultNegation(ASPBodyElement at)

Creates new default negation with the given literal.

Parameters:

at - a classical atom or an aggregate atom

Method Details

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<Predicate> 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 ASPElement

Returns:

all predicates that appear in this formula

getAtoms

public Set<ASPAtom> 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 ASPElement

Returns:

The set of all atoms

substitute

public ASPBodyElement substitute(Term<?> t,
 Term<?> v)

Description copied from interface: ComplexLogicalFormula

Substitutes all occurrences of term "v" in this formula by term "t" and returns the new formula.

Specified by:

substitute in interface ComplexLogicalFormula

Specified by:

substitute in class ASPBodyElement

Parameters:

t - the term to be substituted.

v - the term to substitute.

Returns:

a formula where every occurrence of "v" is replaced by "t".

getSignature

public FolSignature getSignature()

Description copied from interface: Formula

Returns the signature of the language of this formula.

Specified by:

getSignature in interface Formula

Specified by:

getSignature in class ASPElement

Returns:

the signature of the language of this formula.

isWellFormed

public boolean isWellFormed()

Description copied from interface: ComplexLogicalFormula

Checks if this formula is well formed in the logical langauge. What well- formed means is highly language dependent and the documentation of implementing sub classes shall describe the well formed term for the language they model.

Specified by:

isWellFormed in interface ComplexLogicalFormula

Overrides:

isWellFormed in class ASPElement

Returns:

true if the formula is well-formed, false otherwise

isLiteral

public boolean isLiteral()

Returns:

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

getTerms

public Set<Term<?>> getTerms()

Returns:

a set containing all terms of this logical structure

getTerms

public <C extends Term<?>> Set<C> getTerms(Class<C> cls)

Description copied from interface: LogicStructure

Processes the set containing all terms of type C. This method uses the equals method of the given Class and therefore does not add terms which are sub classes of type C to the set.

Type Parameters:

C - the type of terms

Parameters:

cls - The Class structure containing type information about the searched term

Returns:

A set containing all terms of type C of this logical structure

clone

public DefaultNegation clone()

Description copied from interface: SimpleLogicalFormula

Creates a deep copy of this formula

Specified by:

clone in interface ComplexLogicalFormula

Specified by:

clone in interface SimpleLogicalFormula

Specified by:

clone in class ASPElement

Returns:

the cloned formula

getLiteral

public ASPBodyElement getLiteral()

Return the default negated literal

Returns:

the default negated literal

setLiteral

public void setLiteral(ASPBodyElement literal)

Set the default negated literal.

Parameters:

literal - the literal

toString

public String toString()

Overrides:

toString in class Object

printToClingo

public String printToClingo()

Description copied from class: ASPElement

Returns a representation of this ASP element in clingo (potassco) syntax. See https://potassco.org/ for more information.

Overrides:

printToClingo in class ASPElement

Returns:

String representation in clingo syntax

printToDLV

public String printToDLV()

Description copied from class: ASPElement

Returns a representation of this ASP element in DLV syntax. See http://www.dlvsystem.com/html/DLV_User_Manual.html for more information.

Overrides:

printToDLV in class ASPElement

Returns:

String representation in DLV syntax

hashCode

public int hashCode()

Specified by:

hashCode in interface SimpleLogicalFormula

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Specified by:

equals in interface SimpleLogicalFormula

Overrides:

equals in class Object