Input/output control of asynchronous sequential machines

The problem of controlling a finite-state asynchronous sequential machine is examined. Main consideration is given to input/output control, where access to the state of the machine is not available. The objective is to use output feedback to control the machine so as to match a prescribed model. It is shown that necessary and sufficient conditions for the existence of appropriate controllers can be stated in terms of a simple comparison of two numerical matrices. Whenever controllers exist, algorithms for their design are outlined.