Towards a structural characterization of identity, individuality and sortality

Questions regarding the identity and individuality of objects and of sortality of concepts or universals are important questions often raised in the context of an upper ontology. In this paper we present a novel characterization of these concepts based on a structural approach that can be applied in the context of an upper ontology. It provides objective criteria for determining these concepts in function of the structural properties of particulars and universals in structures that model an upper ontology theory. This theory has important applications in the field of conceptual modeling and on inductive reasoning about ontologies.</p