Model-Checking and Simulation for Stochastic Timed Systems

For verification and performance evaluation, system models that can express stochastic as well as real-time behaviour are of increasing importance. Although an integrated stochastic-timed verification procedure is highly desirable, both model-checking and simulation currently fall short of providing a complete, fully automatic verification solution. For model-checking, the problem lies in the extreme expressiveness of such a model, while simulation is limited to stochastic processes and cannot deal with nondeterminism. In this paper, we review the use of stochastic timed automata as an overarching formalism to model stochastic timed systems and present two analysis approaches: Model-checking for the (large) subset corresponding to probabilistic timed automata with deadlines, for which solid implementations are appearing, and simulation, which we have recently shown to be applicable to models that also include spurious nondeterministic choices.