Creating ontological metadata for digital library content and services

We use formal ontologies to represent knowledge about digital library content and services. Formal ontologies define concepts with logic in a frame-inheritance structure. The expressiveness and precision of these structures supports computational reasoning that can be used in important ways. This paper focuses on the creation of ontological metadata. We create ontological content metadata by generating it from MARC (MAchine Readable Cataloging) data. MARC contains much information that is hard to exploit computationally. In particular, relationships between works are implicit in shared values and natural language notes. The conversion process involves specifying an ontological model, mapping MARC to the ontology, and reasoning about the data to create explicit links between works. Service metadata will be supplied by providers who wish to participate fully in a digital library that is implemented as a decentralized multi-agent system. Agents advertise by describing their services in terms of ontologically defined concepts. We reason about these descriptions to organize them into subsumption taxonomies. Agents can then find the best available services to meet their needs by describing their needs, without requiring a priori knowledge of other agents. This infrastructure has demonstrated its usefulness in a multi-agent system organized computational economy. © Springer-Verlag 1998.