Stochastic automata are a formal compositional model for concurrent stochastic timed systems, with general distributions and nondeterministic choices. Measures of interest are defined over schedulers that resolve the nondeterminism. In this paper we investigate the power of various theoretically and practically motivated classes of schedulers, considering the classic complete-information view and a restriction to non-prophetic schedulers. We prove a hierarchy of scheduler classes w.r.t. unbounded probabilistic reachability. We find that, unlike Markovian formalisms, stochastic automata distinguish most classes even in this basic setting. Verification and strategy synthesis methods thus face a tradeoff between powerful and efficient classes. Using lightweight scheduler sampling, we explore this tradeoff and demonstrate the concept of a useful approximative verification technique for stochastic automata.
|Title of host publication||Proceedings of the 21st International Conference on Foundations of Software Science and Computation Structures (FoSSaCS 2018)|
|Editors||Christel Baier, Ugo Dal Lago|
|Place of Publication||Cham|
|Number of pages||19|
|Publication status||Published - 1 Jan 2018|
|Name||Lecture Notes in Computer Science|