On the Expressibility of Discrete Event Specified Systems

In this paper we address the question of the expressibility of discrete event speciied systems (DEVS), i.e., we characterize the subclass of dynamical systems which can be homomorphically represented by DEVS models. We show that causal dynamical systems with piecewise constant input and output segment spaces are DEVS-representable. Moreover, DEVS-representable dynamical systems are closed under coupling, i.e., that a valid coupling of DEVS-representable dynamical systems is a DEVS-representable dynamical system. This justiies hierachical, modular construction of both DEVS models and real-world (continuous or discrete) counterpart systems. Furthermore, we investigate a subclass of dynamical systems in detail, viz., discretely interacting continuous systems with internal dynamics speciied by diierential equations. This class is important in the fast developing eld of hybrid autonomous systems control and is amenable to high performance parallel/distributed discrete event simulation.