net.sf.tweety.logics.rdl

Class DefaultTheory

java.lang.Object

net.sf.tweety.logics.rdl.DefaultTheory

All Implemented Interfaces:

BeliefBase

public class DefaultTheory
extends java.lang.Object
implements BeliefBase

Models a default theory in Reiter's default logic, see [R. Reiter. A logic for default reasoning. Artificial Intelligence, 13:81–132, 1980].

Author:

Matthias Thimm, Nils Geilen

Field Summary

Fields

Modifier and Type	Field and Description
private java.util.Collection<DefaultRule>	defaults The set of default rules
private FolBeliefSet	facts The set of facts (first-order formulas).

Constructor Summary

Constructors

Constructor and Description
DefaultTheory() constructs empty default theory
DefaultTheory(FolBeliefSet facts, java.util.Collection<DefaultRule> defaults) constructs a default theory from a knowledge base and a set of defaults

Method Summary

Modifier and Type	Method and Description
(package private) void	addDefault(DefaultRule d) adds default rule
(package private) void	addFact(FolFormula fact) add facts to knowledge base
java.util.Collection<DefaultRule>	getDefaults()
FolBeliefSet	getFacts()
Signature	getSignature() Returns the signature of the language of this knowledge base.
DefaultTheory	ground() Removes Variables by expanding formulas
(package private) void	removeDefault(DefaultRule d) removes default rule
(package private) void	removeFact(FolFormula fact) removes fact from knowledge base
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

facts

private FolBeliefSet facts

The set of facts (first-order formulas).

defaults

private java.util.Collection<DefaultRule> defaults

The set of default rules

Constructor Detail

DefaultTheory

public DefaultTheory()

constructs empty default theory

DefaultTheory

public DefaultTheory(FolBeliefSet facts,
                     java.util.Collection<DefaultRule> defaults)

constructs a default theory from a knowledge base and a set of defaults

Parameters:

facts - the knowledge base

defaults - the defaults

Method Detail

addFact

void addFact(FolFormula fact)

add facts to knowledge base

removeFact

void removeFact(FolFormula fact)

removes fact from knowledge base

addDefault

void addDefault(DefaultRule d)

adds default rule

removeDefault

void removeDefault(DefaultRule d)

removes default rule

getDefaults

public java.util.Collection<DefaultRule> getDefaults()

Returns:

all the default rules

ground

public DefaultTheory ground()

Removes Variables by expanding formulas

Returns:

grounded version of the default theory

getSignature

public Signature getSignature()

Description copied from interface: BeliefBase

Returns the signature of the language of this knowledge base.

Specified by:

getSignature in interface BeliefBase

Returns:

the signature of the language of this knowledge base.

toString

public java.lang.String toString()

Specified by:

toString in interface BeliefBase

Overrides:

toString in class java.lang.Object

getFacts

public FolBeliefSet getFacts()

Returns:

FoL formulas in default theories