Comparing the Efficiency of Asynchronous Systems

A timed process algebra is developed for evaluating the temporal worst-case efficiency of asynchronous concurrent systems. For the sake of simplicity, we use a classical CCS-like algebra where actions may occur arbitrarily within a continuous time interval, yielding arbitrary relative speeds of the components. Via the timed testing approach, asynchronous systems are then related w.r.t. their worst-case efficiency, yielding an efficiency preorder. We show that this preorder can just as well be based on much simpler discrete time and that it can be characterized with some kind of refusal traces. Finally, precongruence results are provided for all operators of the algebra, where prefix, choice and recursion require special attention