KR Conventicle 2008 @ ISG  
Australian
Knowledge Representation Conventicle, 2008

Sponsored by:
                  Intelligent Systems Group (Macquarie University)
                  Intelligent Systems Laboratory (University of Western Sydney)

 

Conventicle Date and Venue:

                      Friday, 7th March 2008;
                      Dunmore Lang College
                      130 -134 Herring Rd, North Ryde

 

How to get to the Conventicle Venue?

Dunmore Lang College is very close to Macquarie Centre. If you are driving, get to Herring Road off Epping Road (to left if coming from Epping, to right if coming from City). Go through a round about. Dunmore Lang College is on the left (please see map here ). Limited onsite parking available in front of the college. Off site parking available on the other side of the Herring Road, as well as on Windsor drive and Lachlan Ave. If you prefer public transportation, take a bus to Macquarie Centre, then walk to Dunmore Lang College.

Organisers:

                      Abhaya Nayak, Macquarie University
                      Maurice Pagnucco, University of New South Wales
                      Yan Zhang , University of Western Sydney

Program Schedule

TimePresentation
9:00 - 9:15      Opening Address
by Prof. Stephen Thurgate, Dean of ICS, Macquarie University.
9:15 - 9:45      Hans Rott, University of Regensburg.
Belief change and free will
9:45 - 10:05      Abhaya Nayak, Macquarie University.
Iterated Belief Contraction
10:05 - 10:25      Arthur Ramer, University of New South Wales.
GM meets Dirichlet: iterated revision of probabilistic beliefs
10:25 - 10:45      COFFEE/TEA BREAK
10:45 - 11:15      Torsten Schaub, University of Potsdam.
Biological Knowledge Representation and Reasoning
11:15 - 11:45      Kewen Wang, Griffith University
Semantic forgetting and its application in the semantic web
11:45 - 12:05      Ka Shu Wong, University of New South Wales
Forgetting on logic programs under strong equivalence
12:05 - 12:25      Ron van der Meyden, University of New South Wales
What, indeed, is intransitive noninterference?
12:25 - 13:30      LUNCH
13:30 - 14:00      Michael Thielscher, University of Dresden.
From General Game Playing to Trading Agents
14:00 - 14:30      John Lloyd, The Australian National University.
A Reasoning System for Quantified Modal Logic
14:30 - 14:50      Wayne Wobcke, University of New South Wales.
An Axiomatization of a Logic for Reasoning about Rational Agents!
14:50 - 15:10      David Rajaratnam, University of New South Wales.
Motivating Resource Bounded Logics
15:10 - 15:30      COFFEE/TEA BREAK
15:30 - 16:30      Panel/Open Session

Talk Abstracts

A Reasoning System for Quantified Modal Logic

John Lloyd
The Australian National University

Abstract:
I will begin with some motivation for the need to consider quantified modal logic, especially for agent applications. Then I will outline a reasoning system for the logic, consisting of a proof component and a computation component that can call each other, and give some illustrations of its use.

Background material for the talk can be found here.

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Iterated Belief Contraction

Abhaya Nayak
Macquarie University

Abstract:
Importance of contraction for belief change notwithstanding, literature on iterated belief change has by and large centered around the issue of iterated belief revision, ignoring the problem of iterated belief contraction. In this paper we examine iterated belief contraction in a principled way, starting with Qualified Insertion, a proposal by Hans Rott. We show that a judicious combination of Qualified Insertion with a well-known Factoring principle leads to what is arguably a pivotal principle of iterated belief contraction. We show that this principle is satisfied by the account of iterated belief contraction modelled by Lexicographic State Contraction, and outline its connection with Lexicographic Revision, Darwiche-Pearl's account of revision as well as Spohn's Ordinal ranking theory.

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Motivating Resource Bounded Logics

David Rajaratnam
University of New South Wales

Abstract:
In this talk I argue that the logic based agent/AI community needs to be more strongly focused on the intractability of classical logic in developing logical models of agent reasoning. The traditional approach has assumed an idealised view of agent reasoning and makes no consideration for the resource and computational limitations of an agent. This approach has been justified based on normative grounds; the intention is to model how an agent should behave, its commitments, rather then how an agent actually behaves, its performance. In this talk I argue against this approach, both on practical as well as philosophical grounds. Instead I argue that agent commitment and performance are inextricably linked and that normative models can only be established empirically, based on the performance of actual agents, rather than theoretically, based on idealised notions of rationality.

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GM meets Dirichlet: iterated revision of probabilistic beliefs

Arthur Ramer
University of New South Wales.

Abstract:
We present solutions to several open problems suggested by Gardenfors in his book Knowledge in Flux. The question is wheter inverse conditioning, imaging and related probability kinematics can be effected as a minimal change. The answers obtained through the use of entropies and graph entropies, and their related Dirichlet generating functions.

A related application deals with Lewis' impossibility lemma for conditional objects. We prove a general nonexistence of atemporal objects in an arbitrary extension of the original probability domain.

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Belief change and free will

Hans Rott
University of Regensburg.

Abstract:
In this talk I begin by giving a very short overview of the history of belief revision research of the past 25 years. An important development is that the objects of revision are now no longer conceived as belief sets (sets of sentences), but rather belief states (which are more complex structures). The classical AGM paradigm used doxastic preferences as structures guiding the revision of belief sets, and the way how these structures were applied was uncontroversial. The move from belief set revision to belief state revision involved the incorporation of doxastic preferences into the notion of a belief state, and the focus of research has shifted on (a fairly large number) methods of revising such preferences. It seems that we need principles for choosing between such methods, and that these principles should in turn count as part of the agent's mental state. Supposing this choice problem can be solved, the same kind of argument can be reiterated. We are thus lead into an infinite regress or, in an alternative presentation of the same problem, into a circularity of the definition of a belief revision function. In the second part of the talk I ask whether the choices involved in belief change might be manifestations of the agent's free will. I argue that this problem arrived at in the history of belief revision research is at least structurally identical with, and perhaps substantially an instantiation of, a well-known problem with free will put forward by Galen Stawson.

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Biological Knowledge Representation and Reasoning

Torsten Schaub
University of Potsdam

Abstract:
Modeling and interacting with and within natural environments constitutes a major challenge in informatics. This ranges from robotics, bio-informatics to health care applications. Common problems in such domains include change, incompleteness (due to partial observability), and inconsistencies. We address these issues by appeal to techniques developed in the area of knowledge representation and reasoning, using action languages and answer set programming as the basic representation and reasoning framework. Although this choice has several benefits like succinct and elaboration tolerant representations as well as the availability of high performance systems that allow for dealing with millions of variables, it is nonetheless a general purpose approach that is sometimes difficult to access for domain experts, like physicians or biologists.

My talk will take up an ongoing project in systems biology and discuss by several examples how domain specific techniques can be used to address a domain experts needs, while remaining fully transparent as regards the underlying reasoning technology.

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From General Game Playing to Trading Agents

Michael Thielscher
University of Dresden

Abstract:
As one of the grand challenges for Artificial Intelligence, General Game Playing (GGP) is concerned with the development of programs that accept formal descriptions of arbitrary games and play these games without human intervention. GGP requires to combine techniques from a wide range of areas, including knowledge representation, reasoning, and game theory. In this talk, we investigate how recent developments in GGP can be applied to the design and analysis of automatic trading platforms and trading agents. Specifically, we will show how the general Game Description Language can be adapted to a high-level, declarative language for specifying arbitrary trading scenarios.

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What, indeed, is intransitive noninterference?

Ron van der Meyden
University of New South Wales

Abstract:
This paper argues that Haigh and Young╦s definition of noninterference for intransitive security policies admits information flows that are not in accordance with the intuitions it seeks to formalise. Several alternative definitions are discussed, which are shown to be equivalent to the classical definition of noninterference with respect to transitive policies. Rushby╦s unwinding conditions for intransitive noninterference are shown to be sound and complete for one of these definitions, TA-security. Access control systems compatible with a policy are shown to be TA-secure, and it is also shown that TA-security implies that the system can be interpreted as an access control system.

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Semantic forgetting and its application in the semantic web

Kewen Wang
Griffith University

Abstract:
The ability of discarding irrelevant information is a key feature that an intelligent agent must possess to adequately handle reasoning tasks. This ability is referred to as variable forgetting (or variable elimination). In this talk we will first examine some requirements for a suitable notion of forgetting in nonmonotonic reasoning and then introduce a semantic notion of forgetting in the setting of answer set programming. We will also briefly outline some applications of forgetting in editing, reusing and merging ontologies for the semantic web.

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An Axiomatization of a Logic for Reasoning about Rational Agents!

Wayne Wobcke
University of New South Wales

Abstract:
We provide a sound and complete axiomatization of Agent Dynamic Logic (ADL), a logic for reasoning about a class of BDI agent architectures. ADL combines Computation Tree Logic, Propositional Dynamic Logic and Rao and Georgeff╦s BDI Logic, and the main definition relates intention to action, enabling a rigorous formal approach to belief, desire and intention that is also computationally grounded in the operational behaviour of agent architectures. The completeness proof incorporates a result from process algebra on equivalence of programs expressed as regular expressions, and extends this result to the BDI agent framework to model the actions, and indirectly the intentions, of an agent.

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Forgetting on logic programs under strong equivalence

Ka-Shu Wong
University of New South Wales

Abstract:
In this talk I will look at the properties that a notion of forgetting on logic programs should have, particularly in relation to strong equivalence on answer set programs. I will then present some results about the forgetting operators which do have these properties.
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