Package edu.upc.fib.inlab.imp.kse.logics.logicschema.domain

Class Literal

java.lang.Object
edu.upc.fib.inlab.imp.kse.logics.logicschema.domain.Literal
Direct Known Subclasses:
BuiltInLiteral, OrdinaryLiteral
public abstract class Literal extends Object
Implementation of the logic literal. Literals might be ordinary (e.g. "Emp(x)"), or built-in (e.g. "x < 4").

A literal should appear, at most, inside the body of one NormalClause. That is, literals should not be reused among several NormalClauses.

  • Constructor Details

    • Literal

      public Literal()

  • Method Details

    • getArity

      public int getArity()
      Returns arity of literal, i.e. the number of terms.
      Returns:
      arity of literal, i.e. the number of terms.

    • getTerms

      public abstract ImmutableTermList getTerms()

    • applySubstitution

      public abstract Literal applySubstitution(Substitution substitution)
      Constructs new Literal after applying the substitution to the literal terms.
      Parameters:
      substitution - substitution to apply.
      Returns:
      a literal after applying the given substitution. The literal will be new if some term has changed, otherwise it will be the same.

    • getUsedVariables

      public Set<Variable> getUsedVariables()
      Returns used variables of literals.
      Returns:
      used variables of literals.

    • accept

      public abstract <T> T accept(LogicSchemaVisitor<T> visitor)

    • canBeNegated

      public boolean canBeNegated()
      Returns true if literal can be negated.
      Returns:
      true if literal can be negated.
      See Also:

    • buildNegatedLiteral

      public Literal buildNegatedLiteral()
      This method constructs a new literal that is the negation of this one.

      E.g. given an ordinary literal "P(x)" it will return a new literal "not(P(x))", or given a built-in literal "x < y" it will return "x >= y"

      Returns:
      a new literal that is the negation of this literal, if this is possible.
      Throws:
      NoNegatableLiteralException - in case the literal cannot be negated.

    • isGround

      public boolean isGround()
      Returns if all its terms of literal are constants, false otherwise.
      Returns:
      true if all its terms of literal are constants, false otherwise.