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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 17: Optimizing Datalog Programs 679
In order to show that r preserves τ nonrecursively, we will attempt to prove the
opposite by trying to construct a counterexample, and if we fail to do so, then
r preserves τ nonrecursively. A counterexample, in this particular case, is a
DB d Ε5ΑΓ(τ) such that (d,r
n
(d)) violates τ. The DB (d
9
r
n
(d)) violates τ if it
has a ground atom
G(JC
0
,Z
0
)
that exhibits a violation of τ, that is, a ground atom
G(JC
0
,Z
0
)
such that for all u>
0
, the DB (d,r
n
(d)) does not have a ground atom of
the form A(x
0
,w
0
). A ground atom G(x
0
,z
0
) of (d,r
n
(d)) that exhibits a viola-
tion of τ must be in r
n
(d) (it cannot be in d, ...
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Publisher Resources

ISBN: 9781483221120