Introduction

• PDEVS formalism:
  • mathematical description of complex discrete systems using components
  • method and book (Zeigler et al.) widely popular
  • but: not used in standard simulation environments
• Basic obstacle for practical PDEVS use:
  • uses Moore architecture (output depends on state, not on input)
  • Mealy only via transitional states
    • → changes the expected order of concurrent events
    • → makes description complicated
    • → behaviour of such components depends on context
  • serious drawback for a library of reusable blocks
• RPDEVS:
  • "revised" PDEVS by Preyser et al.
  • basic goal: make PDEVS fit for real-life libraries
  • allows for Mealy-like behaviour directly
  • changes the way chains of concurrent events are handled
  • notoriously difficult problem, needs more analysis
• Therefore:
  • test PDEVS and RPDEVS with a crucial example
  • has problems in RPDEVS → find a scheme that might work (NSA-DEVS)
  • NSA-DEVS should make handling of concurrent events as clear as possible
  • check that it works