FERPModels: A Certification Framework for Expansion-Based QBF Solving

Modern expansion-based solvers for quantified Boolean formulas (QBFs) are successful in many applications. However, no such solver supports the generation of proofs needed to independently validate the correctness of the solving result and for the extraction of winning strategies which encode concrete solutions to the application problems.In this paper, we present a complete tool chain for proof generation, result validation, and for universal winning strategy extraction in the context of expansion-based solving. In particular, we introduce a proof format for the ∀Exp-Res calculus on which expansion-based solving is founded, implement proof generation in a recent QBF solver, provide a checker for these proofs, and develop a new strategy extraction algorithm.