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CONSTRAINTS
2010

Erratum to "Reformulating table constraints using functional dependencies - an application to explanation generation"

12 years 1 months ago
Erratum to "Reformulating table constraints using functional dependencies - an application to explanation generation"
Abstract. We had claimed that arc-consistency is preserved in a constraint reformulation relying on functional dependencies (Theorem 2 of [2]). We show that the statement of this theorem was too strong by providing a counter-example. However, the result holds for dependencies between pairs of variables, and more generally in restricted settings. 1 Reformulation of Positive Table Constraints We consider the setting in which a constraint c is defined over a subset of the variables in the problem, scope(c). The set of assignments to the variables in scope(c) that satisfy the constraint are specified as an extensionally defined relation, rel(c). A functional dependency in a relation rel(c) is written as F : X y, where X is a set of variables in the scope of c and y is a single variable in the scope of c, i.e. X {y} scope(c). Informally, a functional dependency states that if a pair of tuples in the relation take the same values for the variables in X, they must also take the same value ...
Hadrien Cambazard, Barry O'Sullivan
Added 09 Dec 2010
Updated 09 Dec 2010
Type Journal
Year 2010
Where CONSTRAINTS
Authors Hadrien Cambazard, Barry O'Sullivan
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