Verification in loosely synchronous queue-connected discrete timed automata

  • Authors:

  • Oscar H. Ibarra;Zhe Dang;Pierluigi San Pietro

  • Affiliations:

  • Department of Computer Science, University of California, 93106-5110 Santa Barbara, CA;School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA;Dipartimento di Elettronica e Informazione, Politecnico di Milano, Italy

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2003

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Abstract

We look at a model of a queue system that consists of the following components: 1. Two discrete timed automata W (the "writer") and R ("the reader"). 2. One unrestricted queue that can be used to send messages from W to R. There is no bound on the length of the queue. W and R do not share a global clock and operate in a loosely synchronous way. That is, the absolute value of the difference between the local time of W and the local time of R is always bounded by a positive constant. We show that the binary reachability for these systems is effectively computable, and this result is generalized to the case when there are two queues (one from W to R and the other from R to W) that operate in half-duplex. We then present some properties (e.g., safety, invariance, etc.) that can be verified for loosely synchronous queue-connected discrete timed automata and give an example of a system composed of a sensor and a controller that is verifiable using our results.