A simplification of a conversation design scheme using Petri nets

In the conversation design procedure, the definition of the state of the system is one of the most important aspects. The question is how to identify transitions in Occam programs in order to express them as Petri nets. In the paper, a simplified transition identification method is proposed. Using the robot arm control program of A.M. Tyrrell and D.J. Holding it is shown that the correspondent Petri net graph is simpler than theirs, but the communication state change table is the same. It is also shown that these two methods are equivalent