P. Kannellakis, Elements of Relational Database Theory, in: J. van Leeuwen (Ed.), Handbook of Theoretical Computer Science, vol. B, North Holland, Amsterdam 1990, pp. 1073--1156. Home/Search Document Not in Database Summary Related Articles Check |
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The Expression Of Graph Properties And Graph Transformations In.. - Courcelle (1997) (38 citations) (Correct)
....A nite structure S is represented by means of some coding of the objects of DS and for each R 2 R a list of (R) tuples of codes of the elements of DS . The study of query languages for relational databases has also been a motivation for nite model theory. See the survey by Kannellakis [48] and the book by Abiteboul et al. 1] 1.2 First order logic We let X be a countable alphabet of lowercase letters called individual variables. Let R be a nite set of relation symbols. The atomic formulas are x = y; R(x 1 ; xn ) for x; y; x 1 ; xn 2 X , R 2 R, n = R) The ....
: KANNELLAKIS P., Elements of relational data base theory, \Handbook of Theoretical Computer Science, Vol. B", J. Van Leeuwen ed., Elsevier 1990, pp. 1073-1156.
Optimization Problems: Expressibility, Approximation.. - Behrendt, Compton.. (1993) (Correct)
....Max Sigma 1 is the class Max Efp defined as above with the condition that ( x; S) j [LFP R; z ] u) where is existential. In particular ( x; S) is a formula in existential fixpoint logic [3] or, equivalently, a query in Datalog( i.e. Datalog with negations over the EDBpredicates [14]. However, this class is already too expressive. Proposition 3.5 If P 6= NP, then Max Efp contains non approximable problems. Proof. We consider the following variant of circuit satisfiability. A circuit is described by a finite structure C = V; E; I; out) where (V; E) is a directed acyclic ....
P. Kannellakis, Elements of Relational Database Theory, in: J. van Leeuwen (Ed.), Handbook of Theoretical Computer Science, vol. B, North Holland, Amsterdam 1990, pp. 1073--1156.
Hierarchies in Transitive Closure Logic, Stratified Datalog.. - Grädel, McColm (1994) (3 citations) (Correct)
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P. Kannellakis, Elements of Relational Database Theory, in: J. van Leeuwen (Ed.), Handbook of Theoretical Computer Science, vol. B, North Holland, Amsterdam 1990, pp. 1073--1156.
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