Modular Construction of Fast Asynchronous Systems

A testing scenario in the sense of De Nicola and Hennessy is developed to measure the worst-case efficiency of asynchronous systems using dense time. It is shown that one can equivalently use discrete time, and the resulting testing-preorder is characterized with some kind of refusal traces which are easier than a previous variant. Furthermore, the testing-preorder is refined to a precongruence for standard operators known from process algebras. Beside the usual complications with the choice operator, it turns out that even the prefix operation requires a refinement. Finally, the testing-preorder is compared to those gained from previous approaches