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The magic sets method is used for eecient bottom up evaluation of logic programs. Since its origin, it suuers from the fact that innuence of information passing among predicates has not been suuciently studied. We have recognized the way of information passing as crucial for the eeciency of the method. In this article the ways of information passing are… (More)
This paper describes a method of the efficient query evaluation when uncertainty is involved in a deductive database system. A deductive system enriched with fuzzy logic is able to serve better as a knowledge system. Speeding up its execution makes this system practically useful.
The semantic web is supposed to become a characteristic phenomenon of the worldwide web in the next decade. One of the basic semantic web tools is the XML language. The aim of this paper is to provide information on how web documents written in the XML language can be rewritten into logic forms expressed as Prolog/Datalog programs. The XML language… (More)
This paper addresses the problem of aggregates in an extended version of Dat-alog. It concentrates especially on the problem of aggregate arguments in the process of eecient query evaluation. We have recognized aggregates as useful constructions, substantially increasing the expressive power of the original Datalog language. The presented paper introduces… (More)