Symbiotic-Witch 2: More Efficient Algorithm and Witness Refutation - (Competition Contribution).

Abstract The new version of the witness validator Symbiotic-Witch follows more precisely the (fixed version of the) semantics of verification witnesses. This makes the tool more efficient as it can benefit from sink nodes. Further, the tool can now refute a witness. To sum up, Symbiotic-Witch 2 can confirm or refute violation witnesses of reachability safety , memory safety , memory cleanup , and overflow properties of sequential C programs.