Tech Reports


Semantics for Interoperability: Relating Ontologies and Schemata

Trevor Bench-Capon, Grant Malcom and Michael Shave


Any builder of an information system starts from some conceptualisation of the domain, which embodies a number of fundamental assumptions about that domain. Often these underlying assumptions remain implicit, but in sharing information across different systems, it is important to be aware of them. In knowledge based systems these assumptions are often made explicit by producing an ontology, an explicit formalisation of the conceptualisation of the domain, which form a significant part of approaches to knowledge managemnet and can be used to facilitate sharing and reuse between divergent but compatible conceptualisations. These underlying assumptions are equally pertinent if we want databases to interoperate. Recent work has suggested that the information contained in their schemata is insufficient, and that the schemata need to be enriched by metadata which makes available these assumptions. In this paper we present a formal approach to ontologies that supports reuse and sharing of information through relationships between compatible conceptualisations. This general approach is then extended to database schemata, which allows us to characterise precisely the relationships between schemata and ontologies, and to give some foundations for understanding how these concepts can be used to facilitate interoperability of heterogeneous information systems. Our main results give a correctness criterion for relationaships between schemata, and show that compatible schemata can be combined to provide an appropriate language for interoperation. We also outline a relationship of conformance between schemata and ontologies that provides a basis for mechanisms supporting interoperation at an abstract, conceptual level.

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