In this paper, we discuss integration of multiple ontologies in a formal way. First, we formalize ontology as combination of logical theories with modality. We introduce two types of integration. Combination aspect connects heterogeneous aspects in which aspect theories are simply merged. On the other hand, category aspect connects homogeneous aspects in which aspect theories are connected with
... [Show full abstract] possibility modality. In the above formalization, inter-aspect theories are defined syntactically but no semantical indication are given. Then we introduce abduction as a heuristics to find inter-aspect theories. Abduction can produce hypothesis which may integrate different aspects. To ensure integration of aspects in hypothesis, we use superposition of hypothesis which try to minimalize instances in hypothesis. 1 Introduction Ontology is not only a key concept to realize intelligent systems systematically but also one to model our intelligent activities because it includes relations between...