Neighborhood and associative query answering

摘要

Cooperative query answering extends the classical notion of query answering to provide neighborhood and associated information. Neighborhood query answering relaxes the query and its answer via abstract representations. To integrate the abstraction view with the subsumption (is-a) and composition (part-of) views of type hierarchy, the notion of type abstraction hierarchy is introduced. To evaluate and control query relaxation, a nearness measure mechanism is provided. Associative query answering provides information conceptually related to, but not explicitly asked by the query. As object association is context sensitive, a DB-Pattern-KB framework is developed that couples domain-specific knowledge and participating objects in localized problem domains via virtual database patterns. Associative query answering can then be accomplished through tracing the behavior dependencies among cooperating objects in those problem domains. Such a framework allows related databases and knowledge bases to be linked dynamically in various contexts yet be maintained relatively independent of each other. The proposed approach has been implemented in the cooperative database system tested, CoBase, at UCLA. Our experience reveals that the proposed techniques are effective for cooperative query answering.