Fig. 1. Freuderfest location The propagation process is also referred to as local consistency enforcement since new constraints illustrate clearer what values are allowed. In general, the gener- ation of unary constraints, i.e., removing values from domains, which has lower overhead, has been more successful in solvers, specially when repeatedly ap- plied on subproblems during backtrack- ing. Techniques where all applied opera- tions result only in redundant constraints or in the splitting of the search space guarantee that no solution is lost. Those techniques guaranteeing to find a solu- tion whenever a solution exists are said to be complete. Most past research has focused on complete algorithms, and this is being identified as something that may change in the near future.
