On Automata with Boundary
  We present a theory of automata with boundary for designing, modelling and analysing distributed systems. Notions of behaviour, design and simulation appropriate to the theory are defined. The problem of model checking for deadlock detection is discussed, and an algorithm for state space reduction in exhaustive search, based on the theory presented here, is described. Three examples of the application of the theory are given, one in the course of the development of the ideas and two as illustrative examples of the use of the theory. 
R. Gates, P. Katis, N. Sabadini, R.F.C. Walters