Belief Contraction in Web-Ontology Languages

Previous works have shown that the AGM theory cannot be used as the basis for defining contraction operators for several ontology representation languages. In this paper, we examine the postulate of relevance which has been proposed in the belief revision literature as a more intuitive alternative to the AGM postulate of recovery. Even though relevance and recovery have been proven to be equivalent in the presence of the other AGM postulates in classical logics, we show that this is not true for non-classical ones. Based on this fact, we are able to show that the relevance postulate is a very attractive alternative to recovery for ontology evolution, as it can be used to define contraction operators in all interesting ontology representation languages.