Abhaya Nayak

Macquarrie University

Tuesday, January 14th @ 11:30pm, ASB 9896

Dynamic Belief Revision Operators

The AGM approach to belief change is not geared to provide a decent account of iterated belief change. Darwiche and Pearl have sought to extend the AGM proposal in an interesting way to deal with this problem. We show that the
original Darwiche-Pearl approach is, on the one hand, excessively strong and, on the other rather limited in scope. The later Darwiche-Pearl approach, we argue, although addresses the first problem, still remains rather permissive. We address both these issues by (1) assuming a dynamic revision operation that changes to a new revision operation after each instance of belief change, and (2) strengthening the Darwiche-Pearl proposal. Moreover, we provide constructions of this dynamic revision operation via entrenchment kinematics as well as a simple form of lexicographic revision, and prove representation results connecting these accounts.

Keywords: Iterated belief change, entrenchment kinematics, lexicographic revision, unary revision.