AC-*: A Configurable, Generic and Adaptive Arc Consistency Algorithm

In this paper, we present AC-*, a new configurable, generic and adaptive algorithm for establishing arc consistency for binary constraints. AC-* is configurable, that is by combining some parameters AC-* corresponds to any existing AC algorithm: AC-3, AC-4, AC-6, AC-7, AC-2000, AC-2001, AC-8, AC-3

d

, AC-3.2 and AC-3.3. AC-* is generic, like AC-5, because it may take into account the structure of the constraints.

AC-* is adaptive because the underlining algorithm can be changed during the computation in order to use the most efficient one. This new algorithm leads to a new nomenclature of the AC algorithms which is based on the different features used by the algorithm like the values that are reconsidered when a domain is modified, or the fact that bi-directionality is taken into account, or the way a new support is sought. This new nomenclature shows that several new possible combinations are now possible. That is, we can easily combine some ideas of AC-3 with some ideas of AC-7 and some ideas of AC-2001 with some ideas of AC-6. Some experimental results highlight the advantages of our approach.