The expressive power of valued constraints: Hierarchies and collapses

In this paper, we investigate the ways in which a fixed collection of valued constraints can be combined to express other valued constraints. We show that in some cases, a large class of valued constraints, of all possible arities, can be expressed by using valued constraints over the same domain of...

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Những tác giả chính: Cohen, D, Jeavons, P, Živný, S
Định dạng: Journal article
Ngôn ngữ:English
Được phát hành: Elsevier 2008
Miêu tả
Tóm tắt:In this paper, we investigate the ways in which a fixed collection of valued constraints can be combined to express other valued constraints. We show that in some cases, a large class of valued constraints, of all possible arities, can be expressed by using valued constraints over the same domain of a fixed finite arity. We also show that some simple classes of valued constraints, including the set of all monotonic valued constraints with finite cost values, cannot be expressed by a subset of any fixed finite arity, and hence form an infinite hierarchy.