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 Details

    • 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()
      Returns:
      the default negated literal

    • setLiteral

      public void setLiteral(ASPBodyElement literal)
      Set the default negated literal.
      Parameters:
      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