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Cataloged from PDF version of article.The interest for multimedia database management systems has grown rapidly due to the need for the storage of huge volumes of multimedia data in computer systems. An important building block of a multimedia database system is the query processor, and a query optimizer embedded to the query processor is needed to answer user queries efficiently. Query optimization problem has been widely studied for conventional database systems; however it is a new research area for multimedia database systems. Due to the differences in query processing strategies, query optimization techniques used in multimedia database systems are different from those used in traditional databases. In this paper, a query optimization strategy is proposed for processing spatio-temporal queries in video database systems. The proposed strategy includes reordering algorithms to be applied on query execution tree. The performance results obtained by testing the reordering algorithms on different query sets are also presented. (C) 2003 Elsevier Inc. All rights reserved

Abstract. Automata-based decision procedures commonly achieve optimal complexity bounds. However, in practice, they are often outperformed by sub-optimal (but more local-search based) techniques, such as tableaux, on many practical reasoning problems. This discrepancy is often the result of automata-style techniques global approach to the problem and the consequent need for constructing an extremely large automaton. This is in particular the case when reasoning in theories consisting of large number of relatively simple formulas, such as descriptions of database schemes, is required. In this paper, we propose techniques that allow us to approach a μ-calculus satisfiability problem in an incremental fashion and without the need for re-computation. In addition, we also propose heuristics that guide the problem partitioning in a way that is likely to reduce the size of the problems that need to be solved.

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