A Natively Parallel Proof Framework for Clause-Sharing SAT Solving

Unsatisfiability proofs are valuable artifacts in propositional satisfiability (SAT) since they can provide correctness guarantees and thus complete trust in reported results. In powerful parallel and distributed clause-sharing SAT solvers, existing proof technology either funnels all solver threads' relevant reasoning steps into a single proof file, which leads to scalability problems for large setups and long running times, or checks proof information in parallel in real-time, which is fully scalable but leaves no persistent artifact. We suggest an alternative approach to achieve the best of both worlds. Specifically, we consider parallel proof files that are logged and also checked in parallel. To this end, we introduce PalRUP - an LRUP-based proof format and a bottleneck-free, decentralized parallel checking procedure that only uses the (parallel) file system and is composed of a set of small, sequential trusted components. In evaluations on up to 3072 cores, we observe that our approach allows for low-overhead proof logging during solving and substantially outscales prior proof producing approaches in terms of checking performance.