Belief Revision, Revised

Abstract

This paper studies properties of it erated revisions. First, a trivia li ty r es ult shows that, in the AGM original framework, the only revision oper at ion that satisfies two reasonable properties is the trivial revision. Then, an alternative to the AGM framework for studying beli ef revision and r ationa lity postulates is proposed. Iterated revisions are th e objects of this formalism and the rationa lity postulates deal with properties of it e rat ed revisions. A set of r atio nality postulates is presented, closely r elat ed to the AGM postulates. A representation r es ult shows that those postulates imply serious limitations to the way revisions can cope with the Principle of Minimal Change. Those postulates are not suitab le for belief updat e, but their consideration raises doubts a bout the adeq ua cy of previous treatments of be li ef upd ate.