Concurrent Probabilistic Programs, Or: How to Schedule if You Must

Consider a finite set of processes, such that each one may use randomizations in its course of execution; these processes are running concurrently, under a fair interleaving schedule. We analyze the worst-case probability of termination, i.e., program convergence to a specified set of goal states. Several methods for computing this probability are presented, and characterizations of the special case where it is identically 1 are derived. Specializations of these characterizations to the case of deterministic and nondeterministic programs, and to the case of programs with finite state spaces, are also discussed.