Trace Semantics for Stochastic Systems with Nondeterminism

This paper discusses trace semantics of interactive Markov chains (IMCs) that are a generalisation of continuous-time Markov chains. In IMCs besides probabilistic alternatives there may be a nondeterministic choice between several action-labelled transitions in a state. We analyse several variants of trace equivalences that arise from the different ways one has to resolve nondeterministic branching. Button pushing testing scenarios are used to motivate each abstraction level induced by the trace semantics and associated equivalences are sorted according to their distinguishing power.