jtp.context
Class IterativeDeepening

java.lang.Object
  |
  +--java.beans.beancontext.BeanContextChildSupport
        |
        +--jtp.util.PropertyImporter
              |
              +--jtp.context.IterativeDeepening

All Implemented Interfaces:

BeanContextChild, BeanContextServiceRevokedListener, BeanContextServicesListener, EventListener, Reasoner, Serializable

public class IterativeDeepening

extends PropertyImporter

implements Reasoner

An asking control reasoner that ensures that an iterative deepening search method is used to prove queries.

The maximum depth to which a search for a proof will be performed can be set with setMaxDepth(int). In an iterative deepening search approach, a bounded depth-first search is conducted at a depth of 1, then 2, then 3, and so on up to the maximum depth.

The query passed to process(java.lang.Object) is subsequently passed to the TheoremProver for processing. The Theorem Prover actually constructs a proof tree (but the depth of the proof tree is determined by the IterativeDeepning instance). It is the entry point to the Asking Control Dispatcher, and thus to all the general-purpose and domain-specific asking Reasoners in the system.

See Also:

Serialized Form

Field Summary

Fields inherited from class java.beans.beancontext.BeanContextChildSupport

beanContext, beanContextChildPeer, pcSupport, rejectedSetBCOnce, vcSupport

Constructor Summary

IterativeDeepening()

Method Summary

boolean	acceptable(Object o) All goals are acceptable to this reasoner.
int	getMaxDepth() Returns the maximum depth to which a search for a proof of a query will be performed.
int	getStartingDepth() Returns the depth of the initial bounded depth-first search for a proof to a query.
Reasoner	getTheoremProver() Returns the Theorem Prover.
Tracer	getTracer()
boolean	getTrimDeepSolutions() When true, proofs that have a proof tree with a depth greater than the depth of the current bounded depth-first search are discarded.
boolean	getTrimShallowSolutions() When true, proofs that have a proof tree with a depth less than the depth of the current bounded depth-first search are discarded.
ReasoningStepIterator	process(Object goal) This method attempts to find proof for the goal.
void	setMaxDepth(int v) Sets the maximum depth to which a search for a proof of a query will be performed.
void	setStartingDepth(int v) Sets the depth of the initial bounded depth-first search for a proof to a query.
void	setTheoremProver(Reasoner v) Sets the Theorem Prover which actually constructs proofs of queries and provides access to the AskingControlDispatcher and all of the child asking Reasoners of the system.
void	setTracer(Tracer v)
void	setTrimDeepSolutions(boolean v) Sets a flag determining whether or not to discard deep solutions.
void	setTrimShallowSolutions(boolean v) Sets a flag determining whether or not to discard shallow solutions.

Methods inherited from class jtp.util.PropertyImporter

getImportedProperties, initializeBeanContextResources, setImportedProperties

Methods inherited from class java.beans.beancontext.BeanContextChildSupport

addPropertyChangeListener, addVetoableChangeListener, firePropertyChange, fireVetoableChange, getBeanContext, getBeanContextChildPeer, isDelegated, releaseBeanContextResources, removePropertyChangeListener, removeVetoableChangeListener, serviceAvailable, serviceRevoked, setBeanContext, validatePendingSetBeanContext

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

IterativeDeepening

public IterativeDeepening()

Method Detail

getTracer

public Tracer getTracer()

setTracer

public void setTracer(Tracer v)

getTheoremProver

public Reasoner getTheoremProver()

Returns the Theorem Prover.

Returns:

Theorem Prover

See Also:

setTheoremProver(jtp.Reasoner)

setTheoremProver

public void setTheoremProver(Reasoner v)

Sets the Theorem Prover which actually constructs proofs of queries and provides access to the AskingControlDispatcher and all of the child asking Reasoners of the system. At this time, the argument must be an instance of ModelEliminationReasoner.

Parameters:

v - an asking Reasoner to be used as the Theorem Prover

getMaxDepth

public int getMaxDepth()

Returns the maximum depth to which a search for a proof of a query will be performed.

Returns:

maximum depth to which inferencing occurs

setMaxDepth

public void setMaxDepth(int v)

Sets the maximum depth to which a search for a proof of a query will be performed.

Parameters:

v - maximum depth to which inferencing occurs

getStartingDepth

public int getStartingDepth()

Returns the depth of the initial bounded depth-first search for a proof to a query. The default value is 1.

Returns:

initial depth of search

setStartingDepth

public void setStartingDepth(int v)

Sets the depth of the initial bounded depth-first search for a proof to a query. The default value is 1.

Parameters:

v - initial depth of search

getTrimShallowSolutions

public boolean getTrimShallowSolutions()

When true, proofs that have a proof tree with a depth less than the depth of the current bounded depth-first search are discarded. When false, they are returned.

Returns:

true if shallow solutions are discarded; false otherwise

setTrimShallowSolutions

public void setTrimShallowSolutions(boolean v)

Sets a flag determining whether or not to discard shallow solutions.

Parameters:

v - true if shallow solutions are to be discarded; false otherwise

See Also:

getTrimShallowSolutions()

getTrimDeepSolutions

public boolean getTrimDeepSolutions()

When true, proofs that have a proof tree with a depth greater than the depth of the current bounded depth-first search are discarded. When false, they are returned.

Returns:

true if deep solutions are discarded; false otherwise

setTrimDeepSolutions

public void setTrimDeepSolutions(boolean v)

Sets a flag determining whether or not to discard deep solutions.

Parameters:

v - true if deep solutions are to be discarded; false otherwise

See Also:

getTrimDeepSolutions()

process

public ReasoningStepIterator process(Object goal)
                              throws ReasoningException

Description copied from interface: Reasoner

This method attempts to find proof for the goal. It returns an enumeration of reasoning steps that correspond to alternative proofs for the goal. Consequently, the items of the enumeration can actually belong to different models of the goal sentence, and have incompatible variable assignments.

Example. A reasoner that performs unification of the goal with facts in a knowledge base can return the following enumeration for the goal (parent joe ?x):

1. A reasoning step proving (parent joe fred) with variable assignment ?x=fred,
2. A reasoning step proving (parent joe mary) with variable assignment ?x=mary.

Specified by:

process in interface Reasoner

Parameters:

goal - the goal: either a query or an assertion

Returns:

an iterator over completed proofs of the goal

ReasoningException

acceptable

public boolean acceptable(Object o)

All goals are acceptable to this reasoner.

Specified by:

acceptable in interface Reasoner

Returns:

true