Definition of NSA-DEVS

• Basic ideas of NSA-DEVS:
  • based on RPDEVS, i.e.
    • only one transition function δ(s, x)
    • only one output function λ(s, x)
  • state transition times always > 0, may be infinitesimal
  • each component has an input delay τ > 0, generally infinitesimal
  • behaviour
    • external event at t → call of λ and δ at t + τ
    • internal event at t → call of λ and δ at t
  • strict Mealy-type behaviour impossible
• Delay times:
  • lots of additional parameters
  • τ = ε should work almost always (hopefully)
  • "transient states" have delay ε mostly (hopefully)
  • finetuning of infinitesimal delays
    • sometimes necessary (e.g. for singleserver)
    • can be used to order "concurrent" events explicitely
• NSA-DEVS simulator:
  • uses defaults value τ = ε
  • standard behaviour
    • shows state change and output values only at the end of an infinitesimal episode
  • debugging behaviour
    • user supplies a finite value for ε
    • behaviour at infinitesimal scale becomes visible