net.sf.tweety.arg.lp.reasoner

Class ArgumentationReasoner

java.lang.Object

net.sf.tweety.arg.lp.reasoner.ArgumentationReasoner

All Implemented Interfaces:

QualitativeReasoner<ArgumentationKnowledgeBase,Argument>, Reasoner<java.lang.Boolean,ArgumentationKnowledgeBase,Argument>

Direct Known Subclasses:

LiteralReasoner

public class ArgumentationReasoner
extends java.lang.Object
implements QualitativeReasoner<ArgumentationKnowledgeBase,Argument>

This class models a reasoner for extended logic programming based arguments using the fixpoint semantics from [1] parameterised by a notion of attack x for the opponent and another notion of attack y as a defense for the proponent. This base implementation only allows to query whether an argument A is x/y-justified in a ELP P. A is called x/y-acceptable wrt. a set of arguments S if for every argument B in P such that (B,A) \in x there exists an argument C \in S such that (C,B) \in y. The set of acceptable arguments for P is defined as the fixpoint J_{P,x/y} of the function F_{P,x/y}(S) = { A | A is x/y-acceptable with regard to S} In [1] it is shown that J_{a/u} equals Dung's grounded semantics, J_{u/su} equals the well founded semantics for normal logic programs and J_{u/a} equals the well-founded semantics for logic programs with explicit negation. [1] Ralf Schweimeier and Michael Schroeder: A Parameterised Hierarchy of Argumentation Semantics for Extended Logic Programming and its Application to the Well-founded Semantics. In: Theory and Practice of Logic Programming, 5(1-2):207-242, 2003.

Author:

Sebastian Homann

Field Summary

Fields

Modifier and Type	Field and Description
protected AttackStrategy	attackStrategy
protected AttackStrategy	defenceStrategy

Constructor Summary

Constructors

Constructor and Description
ArgumentationReasoner(AttackStrategy attack, AttackStrategy defence) Creates a new ArgumentationReasoner parameterised by a notion of attack for the opponent and another notion of attack for the defense

Method Summary

Modifier and Type	Method and Description
java.util.Set<Argument>	getDefensibleArguments(ArgumentationKnowledgeBase kb) Returns the set of defensible arguments, i.e.
java.util.Set<Argument>	getJustifiedArguments(ArgumentationKnowledgeBase kb) Returns the set of x/y-justified arguments using a bottom-up fixpoint calculation
java.util.Set<Argument>	getOverruledArguments(ArgumentationKnowledgeBase kb) Returns the set of overruled arguments, i.e.
private boolean	isAcceptable(ArgumentationKnowledgeBase kb, java.util.Set<Argument> arguments, java.util.Set<Argument> defendingArguments, Argument toCheck) Returns true iff the argument toCheck is x/y-acceptable wrt.
boolean	isDefensible(ArgumentationKnowledgeBase kb, Argument arg) An argument is called x/y-defensible if it is neither x/y-justified nor x/y-overruled.
boolean	isOverruled(ArgumentationKnowledgeBase kb, Argument arg) An argument is called x/y-overruled, if it is attacked by an x/y-justified argument.
java.lang.Boolean	query(ArgumentationKnowledgeBase kb, Argument query) Queries the given belief base for the given formula.

Methods inherited from class java.lang.Object

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

Field Detail

attackStrategy

protected AttackStrategy attackStrategy

defenceStrategy

protected AttackStrategy defenceStrategy

Constructor Detail

ArgumentationReasoner

public ArgumentationReasoner(AttackStrategy attack,
                             AttackStrategy defence)

Creates a new ArgumentationReasoner parameterised by a notion of attack for the opponent and another notion of attack for the defense

Parameters:

attack -

defence -

Method Detail

query

public java.lang.Boolean query(ArgumentationKnowledgeBase kb,
                               Argument query)

Description copied from interface: Reasoner

Queries the given belief base for the given formula.

Specified by:

query in interface QualitativeReasoner<ArgumentationKnowledgeBase,Argument>

Specified by:

query in interface Reasoner<java.lang.Boolean,ArgumentationKnowledgeBase,Argument>

Parameters:

kb - a belief base

query - a formula

Returns:

the answer to the query

isOverruled

public boolean isOverruled(ArgumentationKnowledgeBase kb,
                           Argument arg)

An argument is called x/y-overruled, if it is attacked by an x/y-justified argument.

Parameters:

arg - an argument

Returns:

true iff arg is x-attacked by an x/y-justified argument

isDefensible

public boolean isDefensible(ArgumentationKnowledgeBase kb,
                            Argument arg)

An argument is called x/y-defensible if it is neither x/y-justified nor x/y-overruled.

Parameters:

arg - an argument

Returns:

true iff arg is neither x/y-justified nor x/y-overruled.

getJustifiedArguments

public java.util.Set<Argument> getJustifiedArguments(ArgumentationKnowledgeBase kb)

Returns the set of x/y-justified arguments using a bottom-up fixpoint calculation

Returns:

the set of x/y-justified arguments

getOverruledArguments

public java.util.Set<Argument> getOverruledArguments(ArgumentationKnowledgeBase kb)

Returns the set of overruled arguments, i.e. the set of arguments, which are attacked by a justified argument.

Returns:

the set of overruled arguments.

getDefensibleArguments

public java.util.Set<Argument> getDefensibleArguments(ArgumentationKnowledgeBase kb)

Returns the set of defensible arguments, i.e. the set of arguments, that are neither justified nor overruled.

Returns:

the set of defensible arguments.

isAcceptable

private boolean isAcceptable(ArgumentationKnowledgeBase kb,
                             java.util.Set<Argument> arguments,
                             java.util.Set<Argument> defendingArguments,
                             Argument toCheck)

Returns true iff the argument toCheck is x/y-acceptable wrt. the set of defendingArguments. A is called x/y-acceptable wrt. a set of arguments S if for every argument B in P such that (B,A) \in x there exists an argument C \in S such that (C,B) \in y.

Parameters:

arguments -

defendingArguments -

toCheck -

Returns:

true iff toCheck is x/y-acceptable wrt. defendingArguments