Rule Consistency

This paper develops the theory that a set ofrules is consistent if it is not possible that (1)the conditions of the rules in the set are allsatisfied, (2) there is no exception to either one ofthe rules, and (3) the consequences of the rules areincompatible. To this purpose the notion ofconsistency is generalised to make it cover rulesand is relativised to some background of constraints.This theory is formalised by means of Rule Logic, inwhich rules are treated as constraints on thepossible worlds in which they exist. Rule Logicitself is introduced by giving a model-theory forit. It is characterised by means of constraints onworlds that are possible according to Rule Logic.