Nested Rules in Defeasible Logic

Abstract. Defeasible Logic is a rule-based non-monotonic logic with tractable reasoning services. In this paper we extend Defeasible Logic with nested rules. We consider a new Defeasible Logic, called DL ns, where we allow one level of nested rules. A nested rule is a rule where the antecedent or the consequent of the rule are rules themselves. The inference conditions for DL ns are based on reflection on the inference structures (rules) of the particular theory at hand. Accordingly DL ns can be considered an amalgamated reflective system with implicit reflection mechanism. Finally we outline some possible applications of the logic.