SP-DEVS. We would give a model of FD-DEVS of a crosswalk light controller which is used for SP-DEVS in this Wikipedia. where ={?p}; ={!g:0, !g:1, !w:0, !w:1}; ={BG, BW, G, GR, R, W, D}; =BG, (BG)=0.5,(BW)=0.5, (G)=30, (GR)=30,(R)=2, (W)=26, (D)=2; (G,?p)=(GR,0), (s,?p)=(s,0) if s G; (BG)=(!g:1, BW), (BW)=(!w:0, G),(G)=(, G), (GR)=(!g:0, R), (R)=(!w:1, W), (W)=(!w:0, D), (D)=(!g:1, G); Behaviors of FD-DEVS Models FD-DEVS is a sub-class of DEVS A FD-DEVS model, is DEVS where of are the same as those of . Given a state , Given a state and an input event , Given a state , if Given a state , if For details of DEVS behavior, the readers can refer to Behavior of Atomic DEVS Behavior of Ping-Pong Player A Fig. 3. shows an event segment (top) and the associated state trajectory (bottom) of Player A who plays the ping-pong game introduced in Fig. 1. In Fig. 3. the status of Player A is described as (state, lifespan, elapsed time)=() and the line segment of the bottom of Fig. 3. denotes the value of the elapsed time. Since the initial state of Player A is "Send" and its lifetime is 0.1 seconds, the height of (Send, 0.1, ) is 0.1 which is the value of . After changing into (Wait, inf, 0) when is reset by 0, Player A doesn't know when becomes 0 again. However, since Player B sends back the ball to Player A 0.1 second later, Player A gets back to (Send, 0.1 0) at time 0.2. From that time, 0.1 seconds later when Player A's status becomes (Send, 0.1, 0.1), Player A sends back the ball to Player B and gets into (Wait, inf, 0). Thus, this cyclic state transitions which move "Send" to "Wait" back and forth will go forever. Behavior of a Toaster Fig. 4. shows an event segment (top) and the associated state trajectory (bottom) of the left slot of the two-slot toaster introduced in Fig. 2. Like Fig.3, the status of the left slot is described as (state, lifespan, elapsed time)=() in Fig. 4. Since the initial state of the toaster is "I" and its lifetime is infinity, the height of (Wait, inf, ) can be determined by when ?push occurs. Fig. 4. illustrates the case ?push happens at time 40 and the toaster changes into (T, 20, 0). From that time, 20 seconds later when its status becomes