Belief change and dynamic logic

Abstract

In this paper we compare standard ways to perform belief change with attempts to model such change with dynamic modal operators. We address both belief expansion, belief contraction, belief revision, and update. Public announcement logic is an implementation of a belief expansion operator in a dynamic epistemic setting. The postulates of success and minimal change cannot be satisfied in their original AGM formulation. Dynamic doxastic logic provides various implementations of a belief revision operator in a dynamic epistemic setting. We provide an example of the application of such a dynamic doxastic semantics, which can also be seen as a realization of a proposal by Spohn.

The purpose of this paper is to provide an overview of different approaches to dynamic logics for belief change, including some of our own contributions to the area, in a way that is accessible to an interdisciplinary audience. It does not contain new technical results not published elsewhere. However, the comparison of different approaches provides, we hope, new insights not seen before. A final version of this paper may include new technical results.