1. Chapter 4 DEVS Formalism
Basic DEVS Formalism
Examples
Coupled DEVS Specification
Closure Under Coupling
Hierarchical Models

2. Basic DEVS

3. Basic DEVS: Example Scuba Model
Dive
Plan
Emergency
Phone
Call
Response
=dint (“five”) for phase != “five” ,“surface1”, “surface2”
dint (“five”,s ) otherwise //except when already on “five

4. Use Continue(e) to retain next event time of original pulse
Basic DEVS: Example FireOnce Neuron and Modifications
input
state
output
fire
elapsed
time
pulse t
sigma
phase
refract
receptive
refract
input
fire
fireDelay >0
size= 1
output
size)
Use Continue(e) to retain next event time of original pulse

5. Basic DEVS: Example FireOnce Neuron and Modifications (Continued)
input
state
output
fire
elapsed
time
pulse t
sigma
phase
refract
input
fire t
phase
state
refract
sigma
elapsed
time
pulse
size = 3
output

6. Coupled Model Specification
DN = < X , Y, D, {Mi }, {Ii }, {Zi,j } >
X : a set of input events.
Y : a set of output events.
D : an index set (names) for the components of the coupled model.
For each i Î D ,
Mi is a component DEVS model.
For each i Î D È self , Ii is the set of influencees of i .
For each j Î D È self ,
Zi,j : Yi → Xj is the output translation mapping

7. Closure Under CouplingDN
< X , Y, D, {Mi }, {Ii }, {Zi,j }>
DEVS
< X, S, Y, dint, dext, dcon, ta, l >
DEVS
< X, S, Y, dint, dext, dcon, ta, l >
Every DEVS coupled
model has a
DEVS Basic equivalent