An Approach for Solving Large SAT Problems on FPGA

WSAT and its variants are one of the best performing stochastic local search algorithms for the satisfiability (SAT) problem. In this article, we propose an approach for solving large 3-SAT problems on FPGA using a WSAT algorithm. In hardware solvers, it is important to solve large problems efficiently. In WSAT algorithms, an assignment of binary values to the variables that satisfy all clauses is searched by repeatedly choosing a variable in an unsatisfied clause using a heuristic, and flipping its value. In our solver, (1) only the clauses that may be unsatisfied by the flipping are evaluated in parallel to minimize the circuit size, and (2) several independent tries are executed at the same time on the pipelined circuit to achieve high performance. Our FPGA solver can solve larger problems than previous works with less hardware resources, and shows higher performance.