More than 15 years ago, Cleaveland and Hennessy proposed an extension of the process algebra CCS in which some actions may take priority over others. The theory was equipped with a behavioral congruence based on strong bisimulation.
This article gives a full account of the challenges in, and the solutions employed for, defining a semantic theory of observation congruence for this process algebra.Afull-abstraction result is presented whose proof relies on a novel approach based on successive approximations for identifying the largest congruence contained in an intuitive but naïve equivalence. Prioritized observation congruence is also characterized equationally for the class of finite processes, while its utility for system verification is demonstrated by an illustrative example.
One of the challenges in designing distributed, embedded systems is the paucity of formal, executable specification notations that provide support for both real-time and asynchronous communication. This paper describes a timed architecture design language (Timed Architecture Interaction Diagrams or TAID) that, by virtue of its formal, executable semantics, combines the benefits of synchronous specification notations with the advantages of traditional architecture description languages. In addition, TAID provides support for a variety of temporal inter-process communication (IPC) primitives as a native feature of the language, so that the encapsulated communication behavior (captured by real-time "buses" in TAID) may be re-used across designs and serve as specifications for more detailed model implementations.
Rance Cleaveland Last modified: Thu Oct 18 17:15:39 Eastern Daylight Time 2007