Causal Reversibility Implies Time Reversibility

Several notions of reversibility exist in the literature. On the one hand, causal reversibility establishes that an action can be undone provided that all of its consequences have been undone already, thereby making it possible to bring a system back to a past consistent state. On the other hand, time reversibility stipulates that the stochastic behavior of a system remains the same when the direction of time is reversed, which supports efficient performance evaluation. In this paper we show that causal reversibility is a sufficient condition for time reversibility. The study is conducted on extended labeled transition systems. Firstly, they include a forward and a backward transition relations obeying the loop property. Secondly, their transitions feature an independence relation as well as rates for their exponentially distributed random durations. Our result can thus be smoothly applied to concurrent and distributed models, calculi, and languages that account for performance aspects.