Updating epistemic states

Abstract

Belief update is usually defined by means of operators acting on belief sets. We propose here belief update operators acting on epistemic states which convey much more information than belief sets since they express the relative plausibilities of the pieces of information believed by the agent. In the following, epistemic states are encoded as rankings on worlds. We extend a class of update operators (dependency- based updates) to epistemic states, by defining an operation playing the same role as knowledge transmutations [21] do for belief revision.