Query optimization for KBMSs: temporal, syntactic and semantic transformations

The authors describe a framework for query optimization for knowledge base management systems (KBMSs) based on the knowledge representation language Telos. The framework involves temporal and syntactic simplifications and semantic modification of the queries. Temporal simplification attempts to select parts of a knowledge base that are relevant to a query from a temporal viewpoint. Syntactic simplification exploits structural properties of the data model and attempts to transform the query into an equivalent and more efficient one. Semantic transformation uses knowledge specific to the application domain to transform a user-specified query into another form which gets the same answer and is processed efficiently. The three steps were integrated into a global algorithm for query optimization that utilizes all features of the considered KBMS