jdrew.oo.td
Class BackwardReasoner.Goal

java.lang.Object
  jdrew.oo.td.BackwardReasoner.Goal

Enclosing class:

BackwardReasoner

public class BackwardReasoner.Goal
extends java.lang.Object

Goal - contains an atom (atomic formula) to be solved. Each Goal object belongs to exactly one GoalList. Also each Goal can have at most one SubGoalList attached to it at a given time. The SubGoalList is attached by calling attachSubGoalList, and this GoalList forms the children of the Goal in the GoalTree. The possible GoalLists relevant for this Goal are created by first constructing the SubGoalListIterator and then calling next() on this Iterator to generate successively the SubGoalLists. By relevant, we mean that the Goal is unifiable with the head atom of a Definite Clause in the BackwardReasoner's input clauses.

A Goal may be partially or fully solved. A Goal with an attached SubGoalList is fully solved if that SubGoalList is empty, or if all of the Goals in that SubGoalList are solved. In this case we also say that the SubGoalList is solved. Solved is synonymous with fully solved. A Goal or its attached SubGoalList is partially solved if not fully solved and not failed (see below).

A Goal may also become failed, which means that there are no SubGoalLists available for it, or all SubGoalLists available for it are failed GoalLists. A failed GoalList contains at least one failed Goal. A Goal informs the GoalList of which it is a member that is a failed Goal by calling failed(this) on the GoalList. Recall that a Goal knows this only after all of its SubGoalLists have been found to be failed GoalLists, and since this is under programmer control, it is up to the programmer to make the call to failed. Depending on the client program, this method may or may not be used as it is sets variables that are provided only for the user's convenience of record keeping, and do not initiate any other activity in the BackwardReasoner.

Title: OO jDREW

Description: A deductive reasoning engine for Object-Oriented Knowledge Representation in OO RuleML

Copyright: Copyright (c) 2003

Company: National Research Council of Canada

Version:

0.83

Author:

Marcel Ball

Field Summary

static int	HAS_BUILTIN_SOLUTION_STATE
static int	HAS_NAF_SOLUTION_STATE
static int	HAS_NO_BUILTIN_SOLUTION_STATE
static int	HAS_NO_NAF_SOLUTION_STATE
static int	HAS_NO_SUBGOALLIST_STATE
static int	HAS_SUBGOALLIST_STATE
static int	HAS_UNCONSUMED_NAF_SOLUTION_STATE
static int	INITIAL_STATE
static int	NO_AUTO_PROPAGATE
static int	PROPAGATE_EAGERLY
static int	PROPAGATE_WHEN_SOLVED
static int	PROVE_BY_BUILTIN
static int	PROVE_BY_NAF
static int	PROVE_BY_SUBGOALLIST

Method Summary

void	setSymbolIndex()
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

NO_AUTO_PROPAGATE

public static final int NO_AUTO_PROPAGATE

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Constant Field Values

PROPAGATE_WHEN_SOLVED

public static final int PROPAGATE_WHEN_SOLVED

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Constant Field Values

PROPAGATE_EAGERLY

public static final int PROPAGATE_EAGERLY

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Constant Field Values

INITIAL_STATE

public static final int INITIAL_STATE

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Constant Field Values

HAS_SUBGOALLIST_STATE

public static final int HAS_SUBGOALLIST_STATE

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Constant Field Values

HAS_NO_SUBGOALLIST_STATE

public static final int HAS_NO_SUBGOALLIST_STATE

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Constant Field Values

HAS_BUILTIN_SOLUTION_STATE

public static final int HAS_BUILTIN_SOLUTION_STATE

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Constant Field Values

HAS_NO_BUILTIN_SOLUTION_STATE

public static final int HAS_NO_BUILTIN_SOLUTION_STATE

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Constant Field Values

HAS_NAF_SOLUTION_STATE

public static final int HAS_NAF_SOLUTION_STATE

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Constant Field Values

HAS_NO_NAF_SOLUTION_STATE

public static final int HAS_NO_NAF_SOLUTION_STATE

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Constant Field Values

HAS_UNCONSUMED_NAF_SOLUTION_STATE

public static final int HAS_UNCONSUMED_NAF_SOLUTION_STATE

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Constant Field Values

PROVE_BY_SUBGOALLIST

public static final int PROVE_BY_SUBGOALLIST

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Constant Field Values

PROVE_BY_BUILTIN

public static final int PROVE_BY_BUILTIN

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PROVE_BY_NAF

public static final int PROVE_BY_NAF

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Constant Field Values

Method Detail

setSymbolIndex

public void setSymbolIndex()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

Returns:

String