Fault Localization on Verification Witnesses (poster Paper)

Verifiers export violation witnesses, which help independent valida-tors to confirm a reported specification violation. It is assumed that violation witnesses are helpful if they are very precise: ideally, they should describe a single program path for the validator to check. But we claim that this leads verifiers to produce large, detailed wit-nesses that include a lot of unnecessary information that actually hinders validation. We reduce violation witnesses with automated fault localization to only that information which fault localization suspects as fault. We performed a large experimental evaluation on the witnesses produced in the International Competition on Software Verification (SV-COMP 2023) to explore the effect of our reduction. Our experiments show that the witnesses reduced using our approach shrink considerably and can be confirmed better.