Discrete Timed Automata and MONA: Description, Specification and Verification of a Multimedia Stream

MONA implements an efficient decision procedure for the weak second-order logic WS1S, and has already been applied in many non-trivial problems. Among these, we follow on from the work of Smith and Klarlund on the verification of a sliding-window protocol. This paper extends the scope of MONA to the verification of time-dependent protocols. We present Discrete Timed Automata (DTA) as a suitable formalism to specify and verify such protocols. In this paper our case study will be the specification and verification of a multimedia stream. DTA are as much influenced by IO Automata (syntactically) as they are by Timed Automata (semantically). A composition strategy is given to combine a set of synchronising automata, resulting in a product automaton over which safety properties can be verified. Invariance proofs are then performed inductively on the automaton structure. MONA supports the mechanical verification of invariance proofs.