Domain specific ontologies for semantic information brokering on the global information infrastructure

Recent emerging technologies such as internetworking and the World Wide Web (WWW) have significantly expanded the types, availability, and volume of data accessible to an information management system. In this new environment it is imperative to view an information source at the level of its relevant semantic concepts. We propose that these semantic concepts be chosen from pre-existing domain specific ontologies. Domain specific ontologies are used as tools/mechanisms for specifying the ontological commitments or agreements between information users and providers on the information infrastructure. We use domain specific ontologies to tackle the information explosion by the: (a) Re-use and organization of knowledge in pre-existing real world ontologies, achieved by mapping semantic concepts in the ontologies to data structures in the underlying repositories; and (b) Knowledge integration and development of mechanisms to translate information requests across ontologies. We thus provide support for multiple domain specific ontologies as alternate world views on the vast amounts of data. Semantic information brokering is implemented by brokering across domain ontologies based on interontology relationships such as synonyms, hyponyms and hypernyms defined between terms in different ontologies. Information requests are rewritten using these relationships to obtain translations across ontologies. These ideas have been implemented in the OBSERVER system, the algorithms for which are discussed in this paper.