Revealing vs. Concealing: More Simulation Games for Büchi Inclusion

We address the problem of deciding language inclusion between two non-deterministic Büchi automata. It is known to be PSPACE-complete and finding techniques that are efficient in practice is still a challenging problem. We introduce two new sequences of simulation relations, called multi-letter simulations, in which Verifier has to reproduce Refuter’s moves taking advantage of a forecast. We compare these with the multi-pebble games introduced by Etessami. We show that multi-letter simulations, despite being more restrictive than multi-pebble ones, have a greater potential for an incremental inclusion test, for their size grows generally slower. We evaluate this idea experimentally and show that incremental inclusion testing may outperform the most advanced Ramsey-based algorithms by two orders of magnitude.