Rational Defeasible Belief Change

Speaker: Ivan Varzinczak, CRIL, Université d'Artois & CNRS, France.

Tuesday March 22 2022, 11:00, (salle 1Z71 ENS Paris-Saclay and online)

Abstract: In this talk, I will present a formal framework for modelling belief change within a non-monotonic reasoning system. Belief change and non-monotonic reasoning are two areas that are formally closely related, with recent attention being paid towards the analysis of belief change within a non-monotonic environment. In this talk, I consider the classical AGM belief change operators, contraction and revision, applied to a KLM-style defeasible setting. The investigation leads us to the formal characterisation of a number of classes of defeasible belief change operators. For the most interesting classes we need to consider the problem of iterated belief change, generalising the classical work of Darwiche and Pearl in the process. This work involves belief change operators aimed at ensuring logical consistency, as well as the characterisation of analogous operators aimed at obtaining coherence, an important notion within the field of logic-based ontologies.