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CPAIOR
2005
Springer

Filtering Algorithms for the NValue Constraint

11 years 11 months ago
Filtering Algorithms for the NValue Constraint
Abstract. The NValue constraint counts the number of different values assigned to a vector of variables. Propagating generalized arc consistency on this constraint is NP-hard. We show that computing even the lower bound on the number of values is NP-hard. We therefore study different approximation heuristics for this problem. We introduce three new methods for computing a lower bound on the number of values. The first two are based on the maximum independent set problem and are incomparable to a previous approach based on intervals. The last method is a linear relaxation of the problem. This gives a tighter lower bound than all other methods, but at a greater asymptotic cost.
Christian Bessière, Emmanuel Hebrard, Brahi
Added 26 Jun 2010
Updated 26 Jun 2010
Type Conference
Year 2005
Where CPAIOR
Authors Christian Bessière, Emmanuel Hebrard, Brahim Hnich, Zeynep Kiziltan, Toby Walsh
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