The General System has been described in [Zeigler76] and [ZPK00] with the standpoints to define (1) the time base, (2) the admissible input segments, (3) the system states, (4) the state trajectory with an admissible input segment, (5) the output for a given state. A Timed Event System defining the state trajectory associated with the current and event segments came from the class of General System to allows non-deterministic behaviors in it [Hwang2012]. Since the behaviors of DEVS can be described by Timed Event System, DEVS and RTDEVS is a sub-class or an equivalent class of Timed Event System.

Timed Event Systems

A timed event system is a structure where

Behaviors and Languages of Timed Event System

Given a timed event system, the set of its behaviors is called its language depending on the observation time length. Let t be the observation time length. If, t-length observation language of \mathcal{G} is denoted by, and defined as We call an event segment a t-length behavior of \mathcal{G}, if. By sending the observation time length t to infinity, we define infinite length observation language of \mathcal{G} is denoted by, and defined as We call an event segment an infinite-length behavior of \mathcal{G}, if.