PicoSAT is a satisfiability (SAT) solver for boolean variables in
boolean expressions. A SAT solver can determine if it is possible to
find assignments to boolean variables that would make a given set of
expressions true. If it's satisfiable, it can also show a set of
assignments that make the expression true.

Many problems can be broken down into a large SAT problem (perhaps with
thousands of variables), so SAT solvers have a variety of uses.

WWW: http://fmv.jku.at/picosat