Maintaining Arc Consistency through Constraint Retraction

To cope with a growing number of applications, the basic formalism of constraint satisfaction problems has to be augmented in various directions. One of these directions is the concept of dynamic constraint problems i.e. problems to which constraints can be added but also retracted at any time. To handle dynamic problems, it is important to adapt eeciently the solving procedures that are available on static ones. Of particular interest is the arc-consistency enforcement procedure; the goal of the paper is to present an adaptation of it to dynamic problems. Contrary to previous approaches, the one presented here does not rely on any reason maintenance system and consequently has the advantage of a low space complexity. The detailed algorithm of the procedure is given and an experimental evaluation of its performances is displayed. Some beneets gained by the approach regarding exibility and extensibility are highlighted.