to the modular and hierarchical modeling views, as well as its simulation-based analysis capability, the DEVS formalism and its variations have been used in many application of engineering (such as hardware design, hardware/software codesign, communications systems, manufacturing systems) and science (such as biology, and sociology) Formalism Intuitive Example DEVS defines system behavior as well as system structure. System behavior in DEVS formalism is described using input and output events as well as states. For example, for the ping-pong player of Fig. 1, the input event is ?receive, and the output event is !send. Each player, A, B, has its states: Send and Wait. Send state takes 0.1 seconds to send back the ball that is the output event !send, while the Wait state lasts until the player receives the ball that is the input event ?receive. The structure of ping-pong game is to connect two players: Player A 's output event !send is transmitted to Player B 's input event ?receive, and vice versa. In the classic DEVS formalism, Atomic DEVS captures the system behavior, while Coupled DEVS describes the structure of system. The following formal definition is for Classic DEVS [ZKP00]. In this article, we will use the time base, that is the set of non-negative real numbers; the extended time base, that is the set of non-negative real numbers plus infinity. Atomic DEVS An atomic DEVS model is defined as a 7-tuple where is the set of input events; is the set of output events; is the set of sequential states (or also called the set of partial states); is the initial state; is the time advance function which is used to determine the lifespan of a state; is the external transition function which defines how an input event changes a state of the system, where is the set of total states, and is the elapsed time since the last event; is the internal transition function which defines how a state of the system changes internally (when the elapsed time reaches to the lifetime of the state); is the output function where and is a silent event or an unobserved event. This function defines how a state of the system generates an output event (when the elapsed time reaches to the lifetime of the state); The atomic DEVS Model for Ping-Pong Players The atomic DEVS model for player A of Fig. 1 is given Player= such that Both