FORQ-Based Language Inclusion Formal Testing

Abstract We propose a novel algorithm to decide the language inclusion between (nondeterministic) Büchi automata, PSpace -complete problem. Our approach, like others before, leverage notion of quasiorder prune search for counterexample by discarding candidates which are subsumed quasiorder. Discarded guaranteed not compromise completeness algorithm. The novelty our work lies in used discard candidates. introduce FORQs (family right quasiorders) that we obtain adapting family congruences put forward Maler and Staiger 1993. define FORQ-based prove correct instantiate it specific FORQ, called structural induced automaton sign. resulting implementation, Forklift , scales up better than state-of-the-art on variety benchmarks including from program verification theorem proving word combinatorics. Artifact: https://doi.org/10.5281/zenodo.6552870