Ch-sat: a Complete Heuristic Procedure for Satissability Problems

This paper presents CH-SAT, a Complete Heuris-tic procedure for the SATissability problem (SAT) based on local search techniques. CH-SAT aims to combine the ee-ciency of local search and the completeness of memorizing-backtracking. CH-SAT extends successively a consistent partial assignment using a complete assignment as guidance for variable-ordering. To extend the partial assignment, CH-SAT uses a two-step selection strategy to determine the next variable: the selection of an unsatissable clause followed by the selection of a variable in this clause. If the partial assignment can no longer be extended, it is memorized in the form of a new clause before the search restarts. Experiments on Di-macs benchmarks show the interest of CH-SAT for solving some classes of hard instances.