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Foundations of Deductive Databases and Logic Programming
book

Foundations of Deductive Databases and Logic Programming

by Jack Minker
May 2014
Intermediate to advanced content levelIntermediate to advanced
752 pages
35h 3m
English
Morgan Kaufmann
Content preview from Foundations of Deductive Databases and Logic Programming
Chapter
8:
Intelligent Query Answering
295
This rule is transformable by the join in our query Q since "it does not
change" the projection over the attribute "Supplier." We now have to apply
the join transformation and finally obtain the transformed set of rules:
r
3
= Q(x,y,z) Λ Subpart(v,y) —Q(x,v,z);
r
4
= Q(x,y,z) Λ Q(u,y,w) -^Q(x,y,w)
Rule r
4
is our r rule for a join transformation (it is, in fact, a so-called join
dependency). Notice the computational benefit stemming from the rule trans-
formation here. The resulting query (or "view") could be stored economically
by evaluating only the simplified join as described before and leaving th
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Publisher Resources

ISBN: 9781483221120