No abstract

Abstract. Due to the inherent N P -completeness of SAT, many SAT problems currently cannot be solved in a reasonable time. Usually, to tackle a new class of SAT problems, new ad-hoc algorithm must be designed. Another way to solve a new problem is to use a generic solver and employ parallelism to reduce the solve time.In this paper we propose a parallelization scheme for a class of SAT solvers based on the DPLL procedure. The scheme uses dynamic load balancing mechanism based on the work stealing techniques to deal with the irregularity of SAT problems. We parallelize Satz, one of the best generic SAT solvers, with the scheme to obtain a parallel solver called PSatz. The first experimental results on random 3-SAT and a set of well-known structured problems show the efficiency of PSatz. PSatz is freely available and runs on any networked workstations under Unix/Linux.

Abstract. We propose a two-level search strategy to solve a two dimensional circle packing problem. At the first level, a good enough packing algorithm called A1.0 uses a simple heuristic to select the next circle to be packed. This algorithm is itself used at the second level to select the next circle to be packed. The resulted packing procedure called A1.5 considerably improves the performance of the algorithm in the first level, as shown by experimental results. We also apply the approach to solve other CSPs and obtain interesting results.