In this paper we present a methodology for introducing customizable metalogic features in logic-based knowledge representation and reasoning languages. The proposed approach is based on concepts of introspection and reflection previously introduced and discussed by various authors in relevant literature. This allows a knowledge engineer to specify enhanced reasoning engines by defining properties and meta-properties of relations as expressible for instance in OWL. We employ meta-level axiom schemata based upon a naming (reification) device. We propose general principles for extending the semantics of “host” formalisms accordingly. Suitable pre-defined libraries of properties can be made available, while user-defined new schemata are also allowed. We make the specific case of Answer Set Programming (ASP), where such features may be part of software engineering toolkits for this programming paradigm. We show how to extend the Answer Set Programming principles and practice to accommodate the proposed methodology, so as to perform meta-reasoning within the plain ASP semantics (where we mention and discuss approaches where significant extensions are required).
