MiniSat+ is a two-week hack done to enable MiniSat to compete in the new categories of the SAT 2005 competition. Initially, we intended to support both Pseudo-Boolean constraints (i.e. linear constraints over boolean variables) and circuit based SAT input (as opposed to CNF). However, after we finished the conversion of PB-constraints to SAT, we ran out of steam and never finished the other part.

However, the PB part is, arguably, the more interesting one. A number of generalizations of SAT solvers to PB solvers have been proposed (Pueblo, Galena, OPBDP and more), but we felt that the other approach — converting the problem to SAT — had not been invesigated adequately. Our hope was to provide a point of reference for the proper generalizations of SAT to PB, so that the merit of such an approach could be evaluated. Therefore MiniSat+ provides multiple ways of translating PB constraints to clauses.

For the PB evaluation 2005, we provided a top-level heuristic to choose between the translation methods. To our surprise, MiniSat+ solved more problem than any of the other 6 dedicated PB solvers did, and also seemed to one of the few solvers not being visibly buggy (modulo giving the wrong exitcode for SATISFIABLE instances without an objective function).

To download the source code and statically linked Linux binaries, click here. A paper published in JSAT 2006 describing the methods used in MiniSat+ is available here.