Variations on parallel explicit emptiness checks for generalized Büchi automata

We present new parallel explicit emptiness checks for LTL model checking. Unlike existing parallel emptiness checks, these are based on a strongly connected component (SCC) enumeration and support generalized Büchi acceptance, and require no synchronization points or recomputing procedures. A salient feature of our algorithms is the use of a global union-find data structure in which multiple threads share structural information about the automaton checked. Besides these basic algorithms, we present one architectural variant isolating threads that write to the union-find, and one extension that decomposes the automaton based on the strength of its SCCs to use more optimized emptiness checks. The results from an extensive experimentation of our algorithms and their variations show encouraging performances, especially when the decomposition technique is used.