SAT-Based Software Certification

We formalize a notion of witnesses for satisfaction of linear temporal logic specifications by infinite state programs. We show how such witnesses may be constructed via predicate abstraction, and validated by generating verification conditions and proving them. We propose the use of SAT-based theorem provers and resolution proofs in proving these verification conditions. In addition to yielding extremely compact proofs, a SAT-based approach overcomes several limitations of conventional theorem provers when applied to the verification of programs written in real-life programming languages. We also formalize a notion of witnesses of simulation conformance between infinite state programs and finite state machine specifications. We present algorithms to construct simulation witnesses of minimal size by solving pseudo-Boolean constraints. We present experimental results on several non-trivial benchmarks which suggest that a SAT-based approach can yield extremely compact proofs, in some cases by a factor of over 10, when compared to existing non-SAT-based theorem provers.