Decidability and Complexity Results for Timed Automata and Semi-linear Hybrid Automata

  • Authors:
  • Joseph S. Miller

  • Affiliations:
  • -

  • Venue:
  • HSCC '00 Proceedings of the Third International Workshop on Hybrid Systems: Computation and Control
  • Year:
  • 2000

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Abstract

We define a new class of hybrid automata for which reachability is decidable--a proper superclass of the initialized rectangular hybrid automata--by taking parallel compositions of simple components. Attempting to generalize, we encounter timed automata with algebraic constants. We show that reachability is undecidable for these algebraic timed automata by simulating two-counter Minsky machines. Modifying the construction to apply to parametric timed automata, we reprove the undecidability of the emptiness problem, and then distinguish the dense and discrete-time cases with a new result. The algorithmic complexity-- both classical and parametric--of one-clock parametric timed automata is also examined. We finish with a table of computability-theoretic complexity results, including that the existence of a Zeno run is Σ11 -complete for semi-linear hybrid automata; it is too complex to be expressed in first-order arithmetic.