Abstract
Many AI tasks can be formulated as Constraint-Satisfaction problems (CSP), i.e., the assignment of values to variables subject to a set of constraints. While some CSPs are hard, those that are easy can often be mapped into sparse networks of constraints which, in the extreme case, are trees. This paper identifies classes of problems that lend themselves to easy solutions, and develops algorithms that solve these problems optimally. The paper then presents a method of generating heuristic advice to guide the order of value assignments based on both the sparseness found in the constraint network and the simplicity of tree-structured CSPs. The advice is generated by simplifying the pending subproblems into trees, counting the number of consistent solutions in each simplified subproblem, and comparing these counts to decide among the choices pending in the original problem.
This work was supported in part by the National Science Foundation, Grant #DCR 85-01234
This paper is a revision of one that first appeared in the Journal of Artificial Intelligence, V34, 1988, and is reprinted here by permission of the publisher, North-Holland Publishing Co. Amsterdam.
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Dechter, R., Pearl, J. (1988). Network-Based Heuristics for Constraint-Satisfaction Problems. In: Kanal, L., Kumar, V. (eds) Search in Artificial Intelligence. Symbolic Computation. Springer, New York, NY. https://doi.org/10.1007/978-1-4613-8788-6_11
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DOI: https://doi.org/10.1007/978-1-4613-8788-6_11
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