Propagate the Right Thing: How Preferences Can Speed-Up Constraint Solving

We present an algorithm Pref-AC that limits arc consistency (AC) to the preferred choices of a tree search procedure and that makes constraint solving more efficient without changing the pruning and shape of the search tree. Arc consistency thus becomes more scalable and usable for many realworld constraint satisfaction problems such as configuration and scheduling. Moreover, Pref-AC directly computes a preferred solution for treelike constraint satisfaction problems.