Default Reasoning Through Belief Revision Strategy

Abstract

The thesis of this paper is that default reasoning can be accomplished rather naturally if an appropriate strategy of belief revision is employed. The idea is based on the premise that new beliefs introduced into a situation change the structure of current beliefs to accomodate the new beliefs as exceptions. It is easy to characterise these exceptions in beliefs if we extend the belief language to include some modal operator and prefix the exceptions with the operator. This serves to make the exceptions syntactically explicit, which can then be processed in a routine way by a default reasoning theorem prover.