Automatic Verification of Multi-queue Discrete Timed Automata

Abstract

We propose a new infinite-state model, called the Multi-queue Discrete Timed Automaton MQDTA, which extends Timed Automata with queues, but only has integer-valued clocks. Due to careful restrictions on queue usage, the binary reachability (the set of all pairs of configurations (α, β) of an MQDTA such that α can reach β through zero or more transitions) is effectively semilinear. We then prove the decidability of a class of Presburger formulae defined over the binary reachability, allowing the automatic verification of many interesting properties of a MQDTA. The MQDTA model can be used to specify and verify various systems with unbounded queues, such as a real-time scheduler.