jtp.fol
Interface Literal

All Superinterfaces:

Clause, CNFSentence, Substitutable

All Known Implementing Classes:

DefaultLiteral

public interface Literal

extends Clause

This interface represents a first-order logic literal, that is, a simple relation-based sentence of the form (<rel> <arg1> <arg2> …) or (not (<rel> <arg1> <arg2> …)).

Method Summary

List	getArgs() Returns the arguments in this Literal.
Symbol	getRelation() Returns the relation of this Literal.
boolean	isPositive() Returns false if the Literal is negated; true otherwise.

Methods inherited from interface jtp.fol.Clause

literals

Methods inherited from interface jtp.fol.CNFSentence

clauses

Methods inherited from interface jtp.Substitutable

substitute

Method Detail

isPositive

public boolean isPositive()

Returns false if the Literal is negated; true otherwise.

Returns:

true if the Literal positive; false if negative

getRelation

public Symbol getRelation()

Returns the relation of this Literal. Because this is a first-order logic represenatation, relations must always be constant Symbols.

Returns:

relation of this Literal

getArgs

public List getArgs()

Returns the arguments in this Literal.

Returns:

List of arguments