Formula Preprocessing in MUS Extraction

Efficient algorithms for extracting minimally unsatisfiable subformulas (MUSes) of Boolean formulas find a wide range of applications in the analysis of systems, e.g., hardware and software bounded model checking. In this paper we study the applicability of preprocessing techniques for Boolean satisfiability (SAT) in the context of MUS extraction. Preprocessing has proven to be extremely important in enabling more efficient SAT solving. Hence the study of the applicability and the effectiveness of preprocessing in MUS extraction is highly relevant. Considering the extraction of both standard and group MUSes, we focus on a number of SAT preprocessing techniques, and formally prove to what extent the techniques can be directly applied in the context of MUS extraction. Furthermore, we develop a generic theoretical framework that captures MUS extraction problems, and enables formalizing conditions for correctness-preserving applications of preprocessing techniques that are not applicable directly. We experimentally evaluate the effect of preprocessing in the context of group MUS