Simulation Subsumption in Ramsey-Based Büchi Automata Universality and Inclusion Testing

There are two main classes of methods for checking universality
and language inclusion of Büchi-automata: Rank-based methods
and Ramsey-based methods. While rank-based methods have a better
worst-case complexity, Ramsey-based methods have been shown to be
quite competitive in practice. Previously, it was also shown (for universality checking) that a simple subsumption technique, which avoids exploration of certain cases, greatly improves the performance of the Ramsey-based method. Here, we present a much more general subsumption technique for the Ramsey-based method, which is based on using simulation preorder on the states of the Büchi-automata. This technique applies to both universality and inclusion checking, yielding a substantial performance gain over the previously known simple subsumption approach.