Simulation algorithms for coupled DEVS

Given a coupled DEVS model, simulation algorithms are methods to generate the model's legal behaviors, which are a set of trajectories not to reach illegal states. (see behavior of a Coupled DEVS model.) [Zeigler84] originally introduced the algorithms that handle time variables related to lifespan and elapsed time by introducing two other time variables, last event time, , and next event time with the following relations:

and

where denotes the current time. And the remaining time,

is equivalently computed as

apparently .

Based on these relationships, the algorithms to simulate the behavior of a given Coupled DEVS are written as follows.

Algorithm

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algorithm DEVS-coordinator
  Variables:
     parent // parent coordinator
      : // time of last event
      : // time of next event
       // the associated Coupled DEVS model
    when receive init-message(Time t)
        for each   do
            send init-message(t) to child  
         ;
         ;
    when receive star-message(Time t)
        if   then
            error: bad synchronization;
         
        send star-message(t)to  
         ;
         ;
    when receive x-message( , Time t)
        if   and   == false then
            error: bad synchronization;
        for each   do
            send x-message( ,t) to child  
         ;
         ;
    when receive y-message( , Time t)
        for each   do
            send x-message( ,t) to child  
        if   then
            send y-message( , t) to parent;
         ;
         ;

See also

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References

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  • [Zeigler84] Bernard Zeigler (1984). Multifacetted Modeling and Discrete Event Simulation. Academic Press, London; Orlando. ISBN 978-0-12-778450-2.
  • [ZKP00] Bernard Zeigler; Tag Gon Kim; Herbert Praehofer (2000). Theory of Modeling and Simulation (second ed.). Academic Press, New York. ISBN 978-0-12-778455-7.