# Closure properties of constraints

@article{Jeavons1997ClosurePO, title={Closure properties of constraints}, author={Peter Jeavons and David A. Cohen and Marc Gyssens}, journal={J. ACM}, year={1997}, volume={44}, pages={527-548} }

Many combinatorial search problems can be expressed as “constraint satisfaction problems” and this class of problems is known to be NP-complete in general. In this paper, we investigate the subclasses that arise from restricting the possible constraint types. We first show that any set of constraints that does not give rise to an NP-complete class of problems must satisfy a certain type of algebraic closure condition. We then investigate all the different possible forms of this algebraic… Expand

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