ai.krr.fol
Class TruthValue

java.lang.Object
  ai.krr.fol.Sentence
      ai.krr.fol.TruthValue

All Implemented Interfaces:

inf.compilers.SyntaxAdaptable, java.lang.Cloneable, java.lang.Comparable<Sentence>

public final class TruthValue
extends Sentence

A TruthValue is one of the most basic building blocks for a Sentence. It simply consists of a BooleanSymbol.

Author:

Gerhard Wickler

Nested Class Summary

Nested classes/interfaces inherited from class ai.krr.fol.Sentence

Sentence.SubSentenceIterator

Field Summary

static TruthValue	FALSE the TruthValue for FALSE
protected BooleanSymbol	theSy the BooleanSymbol representing the TruthValue
static TruthValue	TRUE the TruthValue for TRUE

Method Summary

protected void	addBoundVariables(java.util.Set<Variable> bound) This function adds the bound Variables in this Sentence to the given Set.
protected void	addConstants(java.util.Set<Symbol> sys) This function adds all the constant Symbols used in this Sentence to the given Set.
protected void	addFreeVariables(java.util.Set<Variable> free, java.util.Set<Variable> bound) This function adds the free Variables in this Sentence to the first given Set.
protected void	addFunctions(java.util.Map<Symbol,java.lang.Integer> sys) This function adds all the function Symbols used in this Sentence to the given Set.
protected void	addPredicates(java.util.Map<NamedSymbol,java.lang.Integer> sys) This function adds all the predicate Symbols used in this Sentence to the given Set.
boolean	booleanValue() This function returns the boolean value of the BooleanSymbol that represents this TruthValue.
TruthValue	clone() Cloning a TruthValue returns this Object.
TruthValue	clone(Substitution s) Cloning a TruthValue returns this Object.
int	compareTo(Sentence stmt) This function compares this Sentence to the given Sentence.
int	compareTo(TruthValue other) This function compares this TruthValue to the given TruthValue.
BooleanSymbol	evaluate(Interpretation ipt, Substitution s) This function evaluates this Sentence under the given Interpretation and Substitution for Variables.
boolean	exceedsDepth(int depth) This function tests whether this Sentence exceeds the given depth which should be a non-negative integer.
int	getClassOrderIndex() This function returns the index used for ordering Sentences across different classes.
int	getDepth() This function returns the nesting depth of this Sentence.
BooleanSymbol	getSymbol() This function returns the Symbol that represents this TruthValue.
int	hashCode() This function returns the hash code of this TruthValue.
protected Sentence	skolemize(boolean isNegated, Term[] uqVars, Substitution s) This function computes a skolemized version of this Sentence.
protected Sentence	toCNF(boolean isNegated) This function returns a new TruthValue which contains the same BooleanSymbol or its negation, depending on the given boolean.
protected Sentence	toDNF(boolean isNegated) This function returns a new TruthValue which contains the same BooleanSymbol or its negation, depending on the given boolean.
java.lang.String	toString() A TruthValue is printed as the contained symbol.

Methods inherited from class ai.krr.fol.Sentence

allSubSentences, getBoundVariables, getConstants, getFreeVariables, getFunctions, getPredicates, prettyPrint, read, skolemize, toClauseForm, toCNF, toDNF, write

Methods inherited from class java.lang.Object

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

Field Detail

FALSE

public static final TruthValue FALSE

the TruthValue for FALSE

TRUE

public static final TruthValue TRUE

the TruthValue for TRUE

theSy

protected final BooleanSymbol theSy

the BooleanSymbol representing the TruthValue

Method Detail

clone

public final TruthValue clone()

Cloning a TruthValue returns this Object.

Specified by:

clone in class Sentence

Returns:

this TruthValue

clone

public final TruthValue clone(Substitution s)

Cloning a TruthValue returns this Object. The given Substitution is ignored.

Specified by:

clone in class Sentence

Parameters:

s - the Substitution that tells us how to replace Variables

Returns:

this TruthValue

getDepth

public final int getDepth()

This function returns the nesting depth of this Sentence. The depth of a TruthValue is defined to be 0.

Specified by:

getDepth in class Sentence

Returns:

the depth of this Sentence when seen as a tree

exceedsDepth

public final boolean exceedsDepth(int depth)

This function tests whether this Sentence exceeds the given depth which should be a non-negative integer.

Specified by:

exceedsDepth in class Sentence

Parameters:

depth - the depth value that is tested for

Returns:

true iff this.getDepth() > depth

getClassOrderIndex

public final int getClassOrderIndex()

This function returns the index used for ordering Sentences across different classes. This index of this class is defined to be 0.

Specified by:

getClassOrderIndex in class Sentence

Returns:

an integer indicating how this type of Sentence is to be ordered with respect to different types of Sentence

compareTo

public int compareTo(Sentence stmt)

This function compares this Sentence to the given Sentence. The order between different kinds of Sentence is arbitrarily defined as (ascending): Atom, Literal, NegatedSentence, ConnectedSentence, BinaryConnectedSentence, QuantifiedSentence.

Specified by:

compareTo in interface java.lang.Comparable<Sentence>

Specified by:

compareTo in class Sentence

Parameters:

stmt - the Sentence to which this Sentence is to be compared

Returns:

0 if the two Sentences are identical; -1 if the given Sentence should come after this Sentence; and +1 if the given Sentence should come before this Sentence

evaluate

public BooleanSymbol evaluate(Interpretation ipt,
                              Substitution s)

This function evaluates this Sentence under the given Interpretation and Substitution for Variables. Note that the given Substitution must ground all the free Variables occurring in this Sentence. If this Sentence is already ground the given Substitution may be null. If all Atoms and Terms occurring in the Sentence have a value assigned by the Interpretation the result will be a BooleanSymbol. Otherwise it will be null.

Specified by:

evaluate in class Sentence

Parameters:

ipt - the Interpretation giving values for Atoms and Terms

s - the Substitution for Variables occurring in this Term

Returns:

the value of this Term under the given Interpretation

getSymbol

public final BooleanSymbol getSymbol()

This function returns the Symbol that represents this TruthValue.

Returns:

the Symbol that makes up this TruthValue

compareTo

public int compareTo(TruthValue other)

This function compares this TruthValue to the given TruthValue. The order between TruthValues is defined by the order of the BooleanSymbols they contain.

Parameters:

other - the TruthValue to which this TruthValue is to be compared

Returns:

0 if the two TruthValues are identical; -1 if the given TruthValues should come after this TruthValue; and +1 if the given TruthValue should come before this TruthValue

booleanValue

public final boolean booleanValue()

This function returns the boolean value of the BooleanSymbol that represents this TruthValue.

Returns:

whether this TruthValue is TRUE

addConstants

protected final void addConstants(java.util.Set<Symbol> sys)

This function adds all the constant Symbols used in this Sentence to the given Set.

Specified by:

addConstants in class Sentence

Parameters:

sys - the Set that will contain all the Constants

addFunctions

protected final void addFunctions(java.util.Map<Symbol,java.lang.Integer> sys)

This function adds all the function Symbols used in this Sentence to the given Set.

Specified by:

addFunctions in class Sentence

Parameters:

sys - the Set that will contain all the function names

addPredicates

protected final void addPredicates(java.util.Map<NamedSymbol,java.lang.Integer> sys)

This function adds all the predicate Symbols used in this Sentence to the given Set.

Specified by:

addPredicates in class Sentence

Parameters:

sys - the Set that will contain all the predicate names

addFreeVariables

protected final void addFreeVariables(java.util.Set<Variable> free,
                                      java.util.Set<Variable> bound)

This function adds the free Variables in this Sentence to the first given Set. Variables in the second given Set are bound and will not be added.

Specified by:

addFreeVariables in class Sentence

Parameters:

free - a Set of free Variables that will be extended

bound - a Set of bound Variables

addBoundVariables

protected final void addBoundVariables(java.util.Set<Variable> bound)

This function adds the bound Variables in this Sentence to the given Set. This implementation does not modify the given Set.

Specified by:

addBoundVariables in class Sentence

Parameters:

bound - a Set of bound Variables that will be extended

skolemize

protected Sentence skolemize(boolean isNegated,
                             Term[] uqVars,
                             Substitution s)

This function computes a skolemized version of this Sentence. The given Variables and Substitution will be ignored. Only the negation is worked into this Sentence.

Specified by:

skolemize in class Sentence

Parameters:

isNegated - whether the Sentence is negated

uqVars - the known universally quantified Variables at this point

s - the Substitution for Variable replacements

Returns:

a new Sentence with no quantification (can be converted to CNF/DNF)

toCNF

protected Sentence toCNF(boolean isNegated)

This function returns a new TruthValue which contains the same BooleanSymbol or its negation, depending on the given boolean.

Specified by:

toCNF in class Sentence

Parameters:

isNegated - whether the TruthValue has to be negated

Returns:

a new TruthValue

toDNF

protected Sentence toDNF(boolean isNegated)

This function returns a new TruthValue which contains the same BooleanSymbol or its negation, depending on the given boolean.

Specified by:

toDNF in class Sentence

Parameters:

isNegated - whether the TruthValue has to be negated

Returns:

a new TruthValue

toString

public java.lang.String toString()

A TruthValue is printed as the contained symbol.

Overrides:

toString in class java.lang.Object

Returns:

the String that represents this TruthValue

hashCode

public final int hashCode()

This function returns the hash code of this TruthValue.

Overrides:

hashCode in class java.lang.Object

Returns:

a positive integer that may be used for hashing