Publications on Belief Revision

David Billington, Grigoris Antoniou, Guido Governatori, and Michael J. Maher.
Revising nonmonotonic belief sets: The case of defeasible logic. In Wolfram Burgard, Thomas Christaller, and Armin B. Cremers, editors, KI-99: Advances in Artificial Intelligence, volume 1701 of LNAI, pages 101-112, Berlin, 1999. Springer-Verlag, Copyrigth © 1999 Springer-Verlag.
Abstract:The revision and transformation of knowledge is widely recognized as a key issue in knowledge representation and reasoning. Reasons for the importance of this topic are the fact that intelligent systems are gradually developed and refined, and that often the environment of an intelligent system is not static but changes over time. Traditionally belief revision has been concerned with revising first order theories. Nonmonotonic reasoning provides rigorous techniques for reasoning with incomplete information. Until recently the dynamics of nonmonotonic reasoning approaches has attracted little attention. This paper studies the dynamics of defeasible logic, a simple and efficient form of nonmonotonic reasoning based on defeasible rules and priorities. We define revision and contraction operators, propose postulates motivated by the form or the intuition of the AGM postulates for classical belief revision, and verify that the operators satisfy the postulates.
 
Paolo Di Giusto and Guido Governatori.
Analytic modal revision for multi-agent systems. In Pedro Barahona and José Júlio Alferes, editors, Progress in Artificial Intelligence, volume 1695 of LNAI, pages 282-296, Berlin, 1999. Springer-Verlag, Copyrigth © 1999 Springer-Verlag.
Abstract:We present two models of hierarchical structured multi-agents, and we describe how to obtain a modal knowledge base from distributed sources. We then propose a computationally oriented revision procedure for modal knowledge bases. This procedure is based on a labelled tableaux calculi supplemented with a formalism to record the dependencies of the formulae. The dependencies are then used to reconstruct the minimal inconsistent sets, and the sub-formulae responsible for the inconsistencies are revised according to well-defined chains of modal functions.
 
Paolo Di Giusto and Guido Governatori.
Modifying is better than deleting: A new approach to base revision. In Evelina Lamma and Paola Mello, editors, AI*IA 99, pages 145-154, Bologna, 1999. Pitagora.
Abstract:We present three approaches to belief base revision, which are examined also in the case in which the sentences in the base are partitioned between those which can and those which cannot be changed; the approaches are shown to be semantically equivalent. A new approach is then presented, based on the modification of individual rules, instead of deletion. The resulting base is semantically equivalent to that generated by the other approaches, in the sense that it has the same models, but the rule part alone has less models, that is, is subjected to a smaller change.
 
Paolo Di Giusto and Guido Governatori.
A new approach to base revision. In Pedro Barahona and José Júlio Alferes, editors, Progress in Artificial Intelligence, volume 1695 of LNAI, pages 327-341, Berlin, 1999. Springer-Verlag, Copyrigth © 1999 Springer-Verlag.
Abstract:We present three approaches to revision of belief bases, which are also examined in the case in which the sentences in the base are partitioned between those which can and those which cannot be changed; the approaches are shown to be semantically equivalent. A new approach is then presented, based on the modification of individual rules, instead of deletion. The resulting base is semantically equivalent to that generated by the other approaches, in the sense that it has the same models, but the rule part alone has fewer models, that is, is subjected to a smaller change.
 
Guido Governatori and Antonino Rotolo.
Changing legal systems: Abrogation and annulment. Part I: Revision of defeasible theories. In Ron van der Meyden and Leon van der Torre, editors, 9th International Conference on Deontic Logic in Computer Science (DEON2008), Lecture Notes in Computer Science. Springer, 2008. Copyrigth © 2008 Springer.
Abstract: In this paper we investigate how to model legal abrogation and annulment in Defeasible Logic. We examine some options that embed in this setting, and similar rule-based systems, ideas from belief and base revision. In both cases, our conclusion is negative, which suggests to adopt a different logical model.
 
Guido Governatori and Antonino Rotolo.
Changing legal systems: Abrogation and annulment. Part II: Temporalised defeasible logic. In Guido Boella, Harko Verhagen, and Muindhar Singh, editors, Proceedings of Normative Multi Agent Systems (NorMAS 2008, Luxembourg 15-16 July 2008.
Abstract: In this paper we propose a temporal extension of Defeasible Logic to model legal modifications, such as abrogation and annulment. Hence, this framework overcomes the difficulty, discussed elsewhere \cite{deon-part1}, of capturing these modification types using belief and base revision.