KNOWLEDGE-LEVEL ANALYSIS OF BELIEF BASE OPERATIONS

Recent developments in philosophical studies of belief revision have l ed to the construction of models that are much closer to actual comput ing systems than the earlier models. An operation of contraction (revi sion) on a logically closed belief set can be obtained by assigning to it a finite belief base and an operation of contraction (revision) on that base. Exact characterizations of such base-generated operations have been obtained. In this way, computational tractability and other realistic properties of operations on finite bases can be combined wit h a precise analysis that is independent of the symbolic representatio n.