Introduction

Shown below is an axiomatic specification of the Mikrokosmos ontology and onomasticon in First-Order Predicate Calculus. The set of concepts in the database constitutes the ontology and the set of instances the onomasticon. Predicates used in this specification are completely disjoint from the set of symbols used in the ontological database (except, perhaps, for the equality predicate `=') and are therefore called ``meta-ontological predicates.''

There is a single, fundamental, meta-ontological predicate, namely, slot. Using this and a set of constants from the ontology, 36 axioms underlying the ontology have been specified below. A few basic predicates--- concept, instance, frame, and ancestor---are defined using the meta-ontological predicate slot. The 36 axioms together define what constitutes a correct and consistent representation in the ontology and what does not. These axioms define the core ontology as it exists today, excluding such possible enhancements as complex concepts, properties having other properties, reification within the ontology, and so on. I believe that this core set of axioms provides a precise framework for discussing the implications of introducing additional features and complexities in ontological representations.