  This article introduces ATAB, a tool that automatically generates pairwise
reachability checks for action trees. Action trees can be used to study the
behaviour of real-world concurrent programs. ATAB encodes pairwise reachability
checks into alternating tree automata that determine whether an action tree has
a schedule where any pair of given points in the program are simultaneously
reachable. Because the pairwise reachability problem is undecidable in general
ATAB operates under a restricted form of lock-based concurrency. ATAB produces
alternating tree automata that are more compact and more efficiently checkable
than those that have been previously used. The process is entirely automated,
which simplifies the process of encoding checks for more complex action trees.
The alternating tree automata produced are easier to scale to large numbers of
locks than previous constructions.
