On extending SAT solvers for PB problems

The use of SAT solvers to handle practical problems has grown dramatically over the last decade. SAT solvers are now mature enough to be used in hardware or software model checkers and to have an impact on our everyday’s life of computer users. Many researchers are working on extensions of the current framework to more general constraints: pseudo-boolean (PB) constraints, satisfiability modulo theories, etc. We present first pseudo boolean constraints and their relationship with plain clauses. We review current available solutions for solving PB-constraints in Conflict Driven Clause Learning solvers, the most successful architecture of SAT solvers for SAT instances resulting from a translation of the initial problem into SAT. Then we focus on the current limits of our own implementation SAT4JPseudo that participated to the three PB evaluations. We conclude by pointing out some features that require attention for building in the future efficient PB solvers within the CDCL architecture.