  Automata expressiveness is an essential feature in understanding which of the
formalisms available should be chosen for modelling a particular problem.
Probabilistic and stochastic automata are suitable for modelling systems
exhibiting probabilistic behavior and their expressiveness has been studied
relative to non-probabilistic transition systems and Markov chains. In this
paper, we consider previous formalisms of Timed, Probabilistic and Stochastic
Timed Automata, we present our new model of Timed Automata with Polynomial
Delay, we introduce a measure of expressiveness for automata we call trace
expressiveness and we characterize the expressiveness of these models relative
to each other under this new measure.
