Topicality In Logic-Based Ontologies

In this paper we examine several forms of modularity in logics as a basis for various conceptions of the topical structure of an ontology. Intuitively, a topic is a coherent fragment of the subject matter of the ontology. Different topics may play different roles: e.g., the main topic (or topics), side topics, or subtopics. If, at the lowest level, the subject matter of an ontology is characterized by the set of concepts of the ontology, a topic is a "coherent" subset of those concepts. Different forms of modularity induce different, more or less cognitively helpful, notions of coherence and thus distinct topical structures.