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Standard approachs to belief change assume that the underlying logic contains classical propositional logic. Recently there has been interest in investigating approaches to belief change, specifically contraction, in which the underlying logic is not as expressive as full propositional logic. In this paper we consider approaches to belief contraction in(More)
The AGM paradigm for belief revision provides a very elegant and powerful framework to reason about idealized agents. The paradigm assumes that the modelled agent is a perfect reasoner with innnite memory. In this paper we propose a framework to reason about non-ideal agents that generalizes the AGM paradigm. We rst introduce a structure to represent an(More)
The operation of contraction (referring to the removal of knowledge from a knowledge base) has been extensively studied in the research field of belief change, and different postulates (e.g., the AGM postulates with recovery, or relevance) have been proposed, as well as several constructions (e.g., partial meet) that allow the definition of contraction(More)
An agent can usually hold a very large number of beliefs. However, only a small part of these beliefs is used at a time. EEcient operations for belief change should aaect the beliefs of the agent locally, that is, the changes should be performed only in the relevant part of the belief state. In this paper we deene a local consequence operator that only(More)
Standard belief change assumes an underlying logic containing full classical proposi-tional logic. However, there are good reasons for considering belief change in less expressive logics as well. In this paper we build on recent investigations by Delgrande on contraction for Horn logic. We show that the standard basic form of contraction, partial meet, is(More)