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Caching can highly improve performance of query processing in distributed databases. In this paper we show how this technique can be used in grid architecture where data integration is implemented by means of updatable views. Views integrate data from heterogeneous sources and provide users with their integrated form. The whole process of integration is(More)
We present a new approach to optimization of query languages using cached results of previously evaluated queries. It is based on the stack-based approach (SBA) which assumes description of semantics in the form of abstract implementation of query/programming language constructs. Pragmatic universality of object-oriented query language SBQL and its precise,(More)
Time Petri nets by Merlin and Farber are a powerful modelling formalism. However, symbolic model checking methods for them consider in most cases the nets which are 1-safe, i.e., allow the places to contain at most one token. In our paper we present a preliminary version of the approach aimed at testing reachability for time Petri nets without this(More)
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