Reasoning About Probabilistic Behavior in Concurrent Systems

Certain aspects of the behavior of concurrent systems are intrinsically probabilistic in nature, e.g., the behavior of imperfect communication media used in network protocols. We address the problem of expressing such behavior in an algebraic calculus for communicating systems. The introduction of probabilistic information in the calculus alleviates the problem of proving liveness, as proving liveness now amounts to proving that its probability is 1. A methodology for proving both safety and liveness is developed and used in proving the correctness of the Alternating Bit Protocol.