A persistent store for large shared knowledge bases

Techniques for managing problems associated with the scalability of large knowledge-based systems are presented. The discussion is based on experience in building a large knowledge-based system and on perceptions regarding future technological requirements to support ongoing development. Achieving persistence for knowledge bases (KBs) is investigated. Persistence refers to storing a knowledge base on a stable storage medium such as a magnetic disk. A knowledge base management system (KBMS) in which a large KB is concurrently developed by a team of collaborating knowledge engineers is proposed. At the heart of the KBMS is a version store, which is a persistent storage structure for a KB. To support the concurrent collaborative work, the version store maintains multiple versions of a KB such that a knowledge engineer can access and modify any version. Retrieve and update operations have been defined on the version store to efficiently access and modify any version. Objects in a version store are clustered to support efficient access of an entire version of the KB or subparts of it. The retrieval algorithm has been validated through simulation. A prototype of the version store has been implemented and is being integrated into the user interface.