Hierarchical interface-based supervisory control: serial case

We present a hierarchical method that decomposes a system into two subsystems, and restricts the interaction of the subsystems by means of an interface. We present a definition for an interface, and define a set of interface consistency properties that can be used to verify if a discrete-event system is nonblocking and controllable. Each clause of the definition can be verified using only one of the two subsystems; thus the complete system model never needs to be constructed, offering significant savings in computational effort. Additionally, the development of clean interfaces facilitates re-use of the component subsystems.