Download Dependencies in Relational Databases by Prof. Dr. Bernhard Thalheim (auth.) PDF

P(xo)) where for all Xo~ there is a k 1~k~, with Xo~ • x~ and for all i , j , l~i

For DRS. (U,Q,dom) the set of dependencies from L{DRS) is not recursive. The decision problem for dependencies is to decide whether a given formula is a dependency. This problem is recursively unsolvable. Based on this theorem, more precisely defined classes of formulas are required for an interpretation of 43 "real world dependency sets" and not only of "real world dependencies•. 1. RM'Wrzp 1~ 1. e. d(P~) 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. e. e. no variable occurs in two different argument positions of a predicate symbol, and only variables which occur in the same argument position of the predicate can be an argument of an equality formula; general embedded implicational dependency (GEID) if where k,p,q ~ 1, 0 ~ 1 , d = Yy, •..

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