Event Clock Automata: From Theory to Practice

Event clock automata (ECA) are a model for timed languages that has been introduced by Alur, Fix and Henzinger as an alternative to timed automata, with better theoretical properties (for instance, ECA are determinizable while timed automata are not). In this paper, we revisit and extend the theory of ECA. We first prove that no finite time abstract language equivalence exists for ECA, thereby disproving a claim in the original work on ECA. This means in particular that regions do not form a time abstract bisimulation. Nevertheless, we show that regions can still be used to build a finite automaton recognizing the untimed language of an ECA. Then, we extend the classical notions of zones and DBMs to let them handle event clocks instead of plain clocks (as in timed automata) by introducing event zones and Event DBMs (EDBMs). We discuss algorithms to handle event zones represented as EDBMs, as well as (semi-) algorithms based on EDBMs to decide language emptiness of ECA.

[1]  Pierre-Yves Schobbens,et al.  The Logic of Event Clocks - Decidability, Complexity and Expressiveness , 1998, J. Autom. Lang. Comb..

[2]  Stavros Tripakis,et al.  Model Checking of Real-Time Reachability Properties Using Abstractions , 1998, TACAS.

[3]  Maria Sorea,et al.  Tempo: A Model Checker for Event-Recording Automata , 2001 .

[4]  Rajeev Alur,et al.  A Theory of Timed Automata , 1994, Theor. Comput. Sci..

[5]  Patricia Bouyer-Decitre.  Modèles et algorithmes pour la vérification des systèmes temporisés , 2002 .

[6]  Mizuhito Ogawa,et al.  Event-Clock Visibly Pushdown Automata , 2009, SOFSEM.

[7]  Sean R Eddy,et al.  What is dynamic programming? , 2004, Nature Biotechnology.

[8]  Jean-François Raskin,et al.  Safraless Procedures for Timed Specifications , 2010, FORMATS.

[9]  Stavros Tripakis,et al.  Kronos: A Model-Checking Tool for Real-Time Systems , 1998, CAV.

[10]  David L. Dill,et al.  Timing Assumptions and Verification of Finite-State Concurrent Systems , 1989, Automatic Verification Methods for Finite State Systems.

[11]  Wang Yi,et al.  UPPAAL 4.0 , 2006, Third International Conference on the Quantitative Evaluation of Systems - (QEST'06).

[12]  Thomas A. Henzinger,et al.  Event-Clock Automata: A Determinizable Class of Timed Automata , 1999, Theor. Comput. Sci..

[13]  Patricia Bouyer,et al.  Timed Automata May Cause Some Troubles , 2002 .

[14]  Deepak D'Souza,et al.  On Timed Automata with Input-Determined Guards , 2004, FORMATS/FTRTFT.

[15]  Patricia Bouyer,et al.  Forward Analysis of Updatable Timed Automata , 2004, Formal Methods Syst. Des..

[16]  Catalin Dima.  Kleene Theorems for Event-Clock Automata , 1999, FCT.