Abstract

The theory of belief revision deals with models of states of belief and transitions between states of belief. The goal of the theory is to describe what should happen when you update a state of belief with new information. In the most interesting case, the new information is inconsistent with what you believe. This means that some of the old beliefs have to be deleted if one wants to remain within a consistent state of belief. A guiding idea is that the change should be minimal so that as few of the old beliefs as possible are given up.A central problem for the theory of belief revision is what is meant by a minimal change of a state of belief. The solution to this problem depends to a large extent on the model of a state of belief that is adopted.