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CPAIOR
2010
Springer

The Increasing Nvalue Constraint

9 years 8 months ago
The Increasing Nvalue Constraint
This paper introduces the Increasing Nvalue constraint, which restricts the number of distinct values assigned to a sequence of variables so that each variable in the sequence is less than or equal to its successor. This constraint is a specialization of the Nvalue constraint, motivated by symmetry breaking. Propagating the Nvalue constraint is known as an NP-hard problem. However, we show that the chain of non strict inequalities on the variables makes the problem polynomial. We propose an algorithm achieving generalized arc-consistency in O(ΣDi) time, where ΣDi is the sum of domain sizes. This algorithm is an improvement of filtering algorithms obtained by the automaton-based or the Slide-based reformulations. We evaluate our constraint on a resource allocation problem.
Nicolas Beldiceanu, Fabien Hermenier, Xavier Lorca
Added 19 Jul 2010
Updated 19 Jul 2010
Type Conference
Year 2010
Where CPAIOR
Authors Nicolas Beldiceanu, Fabien Hermenier, Xavier Lorca, Thierry Petit
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