This paper presents a method of computing a revision of a function-free normal logic program. If an added rule is inconsistent with a program, that is, if it leads to a situation such that no stable model exists for a new program, then deletion and addition of rules are performed to avoid inconsistency. We specify a revision by translating a normal logic program into an abductive logic program with abducibles to represent deletion and addition of rules. To compute such deletion and addition, we propose an adaptation of our top-down abductive proof procedure to compute a relevant abducibles to an added rule. We compute a minimally revised program, by choosing a minimal set of abducibles among all the sets of abducibles computed by a top-down proof procedure.
Abstract We propose an extension of the SLDNF proof procedure for checking integrity constraints in deductive databases. To achieve the effect of the simplification methods investigated by Nicolas [1982], Lloyd, Sonenberg, and Topor [1986], and Decker [1986], we use clauses corresponding to the updates as top clauses for the search space. This builds in the assumption that the database satisfied its integrity constraints prior to the transaction, and that, therefore, any violation of the constraints in the updated database must involve at least one of the updates in the transaction. Different simplification methods can be simulated by different strategies for literal selection and search. The SLDNF proof procedure needs to be extended to use as top clause any arbitrary deductive rule, denial, or negated fact, to incorporate inference rules for reasoning about implicit deletions resulting from other deletions and additions, and to allow an extended resolution step for reasoning forward from negated facts.