A Calculus of Broadcasting Systems

CBS is a simple and natural CCS-like calculus where processes speak one at a time and are heard instantaneously by all others. Speech is autonomous, contention between speakers being resolved nondeterministically,but hearing only happens when someone else speaks.Observationally meaningful laws dier from those of CCS. The changefrom handshake communication in CCS to broadcast in CBS permits severaladvances. (1) Priority, which attaches only to autonomous actions,is simply added to CBS in contrast to CCS, where such actions are theresult of communication. (2) A CBS simulator runs a process by returninga list of values it broadcasts. This permits a powerful combination,CBS with the host language. It yields several elegant algorithms. Onlyprocesses with a unique response to each input are needed in practice, soweak bisimulation is a congruence. (3) CBS subsystems are interfaced bytranslators; by mapping messages to silence, these can restrict hearingand hide speech. Reversing a translator turns its scope inside out. Thispermits a new specification for a communication link: the environmentof each user should behave like the other user.This paper reports the stable aspects of an evolving study