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Download PDF by Hervé Gallaire, Jack Minker, Jean Marie Nicolas: Advances in Data Base Theory: Volume 1

By Hervé Gallaire, Jack Minker, Jean Marie Nicolas

ISBN-10: 1461582970

ISBN-13: 9781461582977

ISBN-10: 1461582997

ISBN-13: 9781461582991

Through the 1970's a concept of knowledge ases started to evolve professional viding a starting place for a few latest instruments and methods. the importance of this idea is commencing to have an effect particu larly with admire to the layout and implementation of the relational version of information bases. To extra the cutting-edge within the conception of information bases, a workshop used to be held in TOulouse, France on December 12-14, 1979. The workshop used to be a sequel to 1 held years formerly and entitled, "Logic and information Base Workshop." As with the sooner paintings store, the conferences have been performed on the centre d'Etudes et de Recherches de l'Ecole Nationale Superieure de l'Aeronautique et de l'Espace de Toulouse (C.E.R.T). we're happy to recognize the monetary help obtained from the path des Recherches, Etudes et concepts d'Armement (D.R.E.T.), and from C.E.R.T. that made the workshop attainable.

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Extra info for Advances in Data Base Theory: Volume 1

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E ~, then The rule is sound. ) = R. , and let I be in SAT(*[R],*[S]). ~ TI (I) and TI (I) = . * TIS. (I). Substituting . 1-1 Ri R. *. TI R . (I» * (* TIs (I», 1h 1 h=l h which concludes the proof. Mixed Rules Up to now we have considered only jds. If fds are also considered then mixed rules, similar to the FD-MVD rules are needed. We present two rules. FD-EJDl (translation rule) X + Y ~ *[XY, XY] FD-EJD2 (mixed subset rule) *[X,Y], S+A~XnY+A, if (X-Y) ns =O, S~XYandAEX-Y. These two rules are translations of the rules FD-MVDl and FD-MVD2 of Beeri, Fagin and Howard [1977], so, in particular, they are sound.

Then X. ). 0 1 - 1 Note that it is quite possible that JC(~ is empty even though DEPC(Xi) is not empty for each Xi in X. Compare this to Theorem 4. 52 BEERI AND VARDI BRANCH COMPLETENESS OF THE RULES In this section we show that our rules are sufficient for deriving all information about branches of jds implied by any given set of fds and total jds. In particular, they allow us to derive all fds and fohds implied by such a set. This result will be proved using three distinct approaches. Each one of these approaches allows us to gain some understanding of the structure of the jds from a specific viewpoint and we feel that it is instructive to study each one of them.

By the induction hypothesis, we have a derivation from the given premises of the jd hR,' Let us project the jd * [RR,+l,R-(RR,+l-S)] that is included in the premises on S is *[R n l' S U (. - S»]. - S». U (,U n J>;c The result J When this jd is substituted for J the last component of hR,' we obtain the desired hR,+l' It follows that there exists a derivation from the premises of the jd hk = *[Rl""'~'S], Substituting *[~ n S] for S in hk we obtain *[{Rl""'~} U (~n S)]. However, each component of R n S is covered by some R.

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Advances in Data Base Theory: Volume 1 by Hervé Gallaire, Jack Minker, Jean Marie Nicolas


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