Specification of a class of discrete event processes and their controllers

The authors address the problem of what can be done if the only thing that is known about a process is the number of times each event has occurred in the life of the process up to a moment in time. More precisely, they consider what class of discrete event systems may be modeled and controlled using only this minimal information. This question is of practical significance because a model requiring only such data is the simplest possible model. It is also computationally very efficient as it requires only some arithmetic operations. An example involving air-traffic control is presented. The example is worked out (almost) entirely using a counter that records the number of times each event has occurred as time goes on. The design of an active or forceful controller that ensures five operating rules is considered. The example involves air-queues waiting to land, ground-queues waiting to take off, and emergency landings