Experiments in formal modelling of a deadlock avoidance algorithm for a CBTC system

This paper presents a set of experiments in formal modelling and verification of a deadlock avoidance algorithm of an Automatic Train Supervision System (ATS). The algorithm is modelled and verified using four formal environment, namely UMC, Promela/SPIN, NuSMV, and mCRL2. The experience gained in this multiple modelling/verification experiments is described. We show that the algorithm design, structured as a set of concurrent activities cooperating through a shared memory, can be replicated in all the formal frameworks taken into consideration with relative effort. In addition, we highlight specific peculiarities of the various tools and languages, which emerged along our experience.