SLAB: A Certifying Model Checker for Infinite-State Concurrent Systems. Systems and protocols combining concurrency and infinite state space occur quite often in practice, but are very difficult to verify automatically. At the same time, if the system is correct, it is desirable for a verifier to obtain not a simple ”yes” answer, but some independently checkable certificate of correctness. We present SLAB — the first certifying model checker for infinite-state concurrent systems. The tool uses a procedure that interleaves automatic abstraction refinement using Craig interpolation with slicing, which removes irrelevant states and transitions from the abstraction. Given a transition system and a safety property to check, SLAB either finds a counterexample or produces a certificate of system correctness in the form of inductive verification diagram.