Boolean Equi-propagation for Optimized SAT Encoding

Amit Metodi, Michael Codish, Vitaly Lagoon, Peter J. Stuckey

Abstract: We present an approach to propagation based SAT encoding, Boolean equi-propagation, where constraints are modelled as Boolean functions which propagate information about equalities between Boolean literals. This information is then applied as a form of partial evaluation to simplify constraints prior to their encoding as CNF formulae. We demonstrate for a variety of benchmarks that our approach leads to a considerable reduction in the size of CNF encodings and subsequent speed-ups in SAT solving times.