MiniSat is a minimalistic, open-source SAT solver, developed to help researchers and developers alike to get started on SAT (Boolean satisfiability problem)
Markov logic networks (MLNs) combine first-order logic with the probabilistic semantics of graphical models. PyMLNs offers you inference and learning tools for MLNs.
Alchemy is a software package providing a series of algorithms for statistical relational learning and probabilistic logic inference, based on the Markov logic representation.