Package net.sf.tweety.logics.cl.semantics

Class RankingFunction

  • All Implemented Interfaces:
    Interpretation<ClBeliefSet,​Conditional>
    public class RankingFunction
extends AbstractInterpretation<ClBeliefSet,​Conditional>
    A ranking function (or ordinal conditional function, OCF) that maps possible worlds of a propositional language to integers.

    See W. Spohn. Ordinal conditional functions: a dynamic theory of epistemic states. In W.L. Harper and B. Skyrms, editors, Causation in Decision, Belief Change, and Statistics, II, pages 105-134. Kluwer Academic Publishers, 1988.
    Author:
    Matthias Thimm

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static java.lang.Integer INFINITY
      Integer used to define infinity.

    • Constructor Summary

      Constructors 
      Constructor Description
      RankingFunction​(PlSignature signature)
      Creates a new ranking function mapping each given interpretation to zero.

    • Method Summary

      Modifier and Type Method Description
      boolean equals​(java.lang.Object other)  
      static boolean falsifies​(PossibleWorld w, Conditional c)
      Checks whether the given possible world w falsifies the given conditional (B|A), i.e.
      void forceStrictness​(java.util.Set<PlFormula> formulas)
      Sets the rank of every interpretation i that does not satisfy the given set of formulas to RankingFunction.INFINITY.
      java.util.Set<PossibleWorld> getPlausibleWorlds()
      Returns all interpretations that are mapped to 0
      java.util.Set<PossibleWorld> getPossibleWorlds()
      Returns all interpretations that are mapped to a rank unequal to INFINITY.
      PlSignature getSignature()
      Returns the signature of the first-order language this ranking function is defined on.
      boolean isNormalized()
      Checkes whether this OCF is normalized, i.e.
      void normalize()
      Normalizes this OCF, i.e.
      java.lang.Integer rank​(PossibleWorld w)
      Gets the rank of the given possible world.
      java.lang.Integer rank​(PlFormula formula)
      Gets the rank of the given formula.
      boolean satisfies​(ClBeliefSet beliefBase)
      Checks whether this interpretation satisfies the given knowledge base.
      boolean satisfies​(Conditional formula)
      Checks whether this interpretation satisfies the given formula.
      static boolean satisfies​(PossibleWorld w, Conditional c)
      Checks whether the given possible world w satisfies the given conditional (B|A), i.e.
      void setRank​(PossibleWorld w, java.lang.Integer value)
      Sets the rank for the given possible world.
      java.lang.String toString()  
      static boolean verifies​(PossibleWorld w, Conditional c)
      Checks whether the given possible world w verifies the given conditional (B|A), i.e.

      • Methods inherited from class java.lang.Object

        getClass, hashCode, notify, notifyAll, wait, wait, wait

    • Field Detail

      • INFINITY

        public static final java.lang.Integer INFINITY
        Integer used to define infinity.

    • Constructor Detail

      • RankingFunction

        public RankingFunction​(PlSignature signature)
        Creates a new ranking function mapping each given interpretation to zero.
        Parameters:
        signature - the signature of the language this ranking function is defined on.

    • Method Detail

      • rank

        public java.lang.Integer rank​(PossibleWorld w)
                       throws java.lang.IllegalArgumentException
        Gets the rank of the given possible world.
        Parameters:
        w - an possible world.
        Returns:
        the rank of the given possible world.
        Throws:
        java.lang.IllegalArgumentException - if the given possible world has no rank in this ranking function.

      • setRank

        public void setRank​(PossibleWorld w,
                    java.lang.Integer value)
        Sets the rank for the given possible world.
        Parameters:
        w - an possible world.
        value - the rank for the possible world.

      • satisfies

        public boolean satisfies​(Conditional formula)
                  throws java.lang.IllegalArgumentException
        Description copied from interface: Interpretation
        Checks whether this interpretation satisfies the given formula.
        Parameters:
        formula - a formula .
        Returns:
        "true" if this interpretation satisfies the given formula.
        Throws:
        java.lang.IllegalArgumentException - if the formula does not correspond to the expected language.

      • satisfies

        public boolean satisfies​(ClBeliefSet beliefBase)
        Description copied from interface: Interpretation
        Checks whether this interpretation satisfies the given knowledge base.
        Parameters:
        beliefBase - a knowledge base.
        Returns:
        "true" if this interpretation satisfies the given knowledge base.

      • forceStrictness

        public void forceStrictness​(java.util.Set<PlFormula> formulas)
        Sets the rank of every interpretation i that does not satisfy the given set of formulas to RankingFunction.INFINITY.
        Parameters:
        formulas - a set of first-order formulas.

      • rank

        public java.lang.Integer rank​(PlFormula formula)
                       throws java.lang.IllegalArgumentException
        Gets the rank of the given formula. Throws an IllegalArgumentException when the language of the formula does not correspond to the language of the interpretations this ranking function is defined on. Otherwise the rank of a formula is defined as the minimal rank of its satisfying interpretations.
        Parameters:
        formula - a formula.
        Returns:
        the rank of the given formula.
        Throws:
        java.lang.IllegalArgumentException - if the languages of the formula does not correspond to the language of the interpretations this ranking function is defined on.

      • normalize

        public void normalize()
        Normalizes this OCF, i.e. appropriately shifts the ranks such that the minimal rank equals zero.

      • isNormalized

        public boolean isNormalized()
        Checkes whether this OCF is normalized, i.e. whether its minimal rank value is zero.
        Returns:
        "true" if this OCF is normalized

      • getPossibleWorlds

        public java.util.Set<PossibleWorld> getPossibleWorlds()
        Returns all interpretations that are mapped to a rank unequal to INFINITY.
        Returns:
        all interpretations that are mapped to a rank unequal to INFINITY.

      • getPlausibleWorlds

        public java.util.Set<PossibleWorld> getPlausibleWorlds()
        Returns all interpretations that are mapped to 0
        Returns:
        all interpretations that are mapped to 0

      • getSignature

        public PlSignature getSignature()
        Returns the signature of the first-order language this ranking function is defined on.
        Returns:
        the signature of the first-order language this ranking function is defined on.

      • verifies

        public static boolean verifies​(PossibleWorld w,
                               Conditional c)
        Checks whether the given possible world w verifies the given conditional (B|A), i.e. whether w satisfies A and B
        Parameters:
        w - a possible world
        c - a conditional.
        Returns:
        "true" if the given possible world verifies the given conditional.

      • falsifies

        public static boolean falsifies​(PossibleWorld w,
                                Conditional c)
        Checks whether the given possible world w falsifies the given conditional (B|A), i.e. whether w satisfies A and not B
        Parameters:
        w - a possible world
        c - a conditional.
        Returns:
        "true" if the given possible world falsifies the given conditional.

      • satisfies

        public static boolean satisfies​(PossibleWorld w,
                                Conditional c)
        Checks whether the given possible world w satisfies the given conditional (B|A), i.e. whether w does not falsify c.
        Parameters:
        w - a possible world
        c - a conditional.
        Returns:
        "true" if the given possible world satisfies the given conditional.

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object

      • equals

        public boolean equals​(java.lang.Object other)
        Overrides:
        equals in class java.lang.Object