Distributed Timed Automata with Independently Evolving Clocks

  • S. Akshay
  • Benedikt Bollig
  • Paul Gastin
  • Madhavan Mukund
  • K. Narayan Kumar
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5201)


We propose a model of distributed timed systems where each component is a timed automaton with a set of local clocks that evolve at a rate independent of the clocks of the other components. A clock can be read by any component in the system, but it can only be reset by the automaton it belongs to.

There are two natural semantics for such systems. The universal semantics captures behaviors that hold under any choice of clock rates for the individual components. This is a natural choice when checking that a system always satisfies a positive specification. However, to check if a system avoids a negative specification, it is better to use the existential semantics—the set of behaviors that the system can possibly exhibit under some choice of clock rates.

We show that the existential semantics always describes a regular set of behaviors. However, in the case of universal semantics, checking emptiness turns out to be undecidable. As an alternative to the universal semantics, we propose a reactive semantics that allows us to check positive specifications and yet describes a regular set of behaviors.


Clock Rate Hybrid Automaton Local Clock Clock Region Clock Valuation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2008

Authors and Affiliations

  • S. Akshay
    • 1
    • 3
  • Benedikt Bollig
    • 1
  • Paul Gastin
    • 1
  • Madhavan Mukund
    • 2
  • K. Narayan Kumar
    • 2
  1. 1.LSV, ENS Cachan, CNRSFrance
  2. 2.Chennai Mathematical InstituteChennaiIndia
  3. 3.The Institute of Mathematical SciencesChennaiIndia

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