… In this paper we extend the PAC learning algorithm due to Clark and Thollard for learning
distributions generated by PDFA to automata whose transitions may take varying time
lengths, governed by exponential distributions. … Here we consider what we call
asynchronous PDFA (AsPDFA), in which each transition has an associated exponential
distribution. We think of this distribution as indicating the ‘time’ or duration of the transition.
Note that there are several models of timed automata in the literature with other meanings …