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12
Model Checking Timed Automata with One or Two Clocks
 IN PROC. CONCUR’04, LNCS 3170
, 2004
"... In this paper, we study model checking of timed automata (TAs), and more precisely we aim at finding efficient model checking for subclasses of TAs. For this, we consider model checking TCTL and TCTL#,# over TAs with one clock or two clocks. First we ..."
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Cited by 19 (3 self)
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In this paper, we study model checking of timed automata (TAs), and more precisely we aim at finding efficient model checking for subclasses of TAs. For this, we consider model checking TCTL and TCTL#,# over TAs with one clock or two clocks. First we
Comparison of the expressiveness of timed automata and time Petri nets
 In Proc. FORMATS’05, vol. 3829 of LNCS
, 2005
"... Abstract. In this paper we consider the model of Time Petri Nets (TPN) “à la Merlin ” where a time interval is associated with the firing of a transition, but we extend it with open intervals. We also consider Timed Automata (TA) as defined by Alur & Dill. We investigate some questions related to ex ..."
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Cited by 12 (5 self)
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Abstract. In this paper we consider the model of Time Petri Nets (TPN) “à la Merlin ” where a time interval is associated with the firing of a transition, but we extend it with open intervals. We also consider Timed Automata (TA) as defined by Alur & Dill. We investigate some questions related to expressiveness for these models: we study the impact of slight variations of semantics for TPN and we compare the expressive power of TA and TPN, with respect to both time language acceptance and weak time bisimilarity. We prove that TA and bounded TPNs (enlarged with strict constraints) are equivalent w.r.t. timed language equivalence, providing an efficient construction of a TPN equivalent to a TA. We then exhibit a TA A such that no TPN (even unbounded) is weakly bisimilar to A. Because of this last result, it is natural to try and identify the (strict) subclass of TA that is equivalent to TPN w.r.t. weak timed bisimilarity. Thus we give some further results: 1) we characterize the subclass TA − of TA that is equivalent to the original model of TPN as defined by Merlin, i.e. restricted to closed intervals, 2) we show that the associated membership problem for TA − is PSPACEcomplete and 3) we prove that the reachability problem for TA − is also PSPACEcomplete.
Comparing the Expressiveness of Timed Automata and Timed Extensions of Petri Nets
"... Time dependant models have been intensively studied for many reasons, among others because of their applications in software verification and due to the development of embedded platforms where reliability and safety depend to a large extent on the time features. Many of the time dependant models w ..."
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Cited by 9 (2 self)
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Time dependant models have been intensively studied for many reasons, among others because of their applications in software verification and due to the development of embedded platforms where reliability and safety depend to a large extent on the time features. Many of the time dependant models were suggested as realtime extensions of several wellknown untimed models. The most studied formalisms include Networks of Timed Automata which extend the model of communicating finitestate machines with a finite number of realvalued clocks, and timed extensions of Petri nets where the added time constructs include e.g. time intervals that are assigned to the transitions (Time Petri Nets) or to the arcs (TimedArc Petri Nets). In this paper, we shall semiformally introduce these models, discuss their strengths and weaknesses, and provide an overview of the known results about the relationships among the models.
State explosion in almostsure probabilistic reachability
, 2007
"... We show that the problem of reaching a state set with probability 1 in probabilisticnondeterministic systems operating in parallel is EXPTIMEcomplete. We then show that this probabilistic reachability problem is EXPTIMEcomplete also for probabilistic timed automata. Key words: probabilistic system ..."
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Cited by 8 (4 self)
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We show that the problem of reaching a state set with probability 1 in probabilisticnondeterministic systems operating in parallel is EXPTIMEcomplete. We then show that this probabilistic reachability problem is EXPTIMEcomplete also for probabilistic timed automata. Key words: probabilistic systems, model checking, computational complexity, formal methods, timed automata 1
When are timed automata weakly timed bisimilar to time Petri nets?
 25TH CONFERENCE ON FOUNDATIONS OF SOFTWARE TECHNOLOGY AND THEORETICAL COMPUTER SCIENCE (FSTTCS 2005), HYDERABAD, INDIA LNCS
, 2005
"... In this paper, we compare Timed Automata (TA) and Time Petri Nets (TPN) with respect to weak timed bisimilarity. It is already known that the class of bounded TPNs is strictly included in the class of TA. It is thus natural to try and identify the subclass T A wtb of TA equivalent to some TPN for t ..."
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Cited by 6 (2 self)
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In this paper, we compare Timed Automata (TA) and Time Petri Nets (TPN) with respect to weak timed bisimilarity. It is already known that the class of bounded TPNs is strictly included in the class of TA. It is thus natural to try and identify the subclass T A wtb of TA equivalent to some TPN for the weak timed bisimulation relation. We give a characterization of this subclass and we show that the membership problem and the reachability problem for T A wtb are PSPACEcomplete. Furthermore we show that for a TA in T A wtb with integer constants, an equivalent TPN can be built with integer bounds but with a size exponential w.r.t. the original model. Surprisingly, using rational bounds yields a TPN whose size is linear.
Simulation and Bisimulation for Probabilistic Timed Automata ⋆
"... Abstract. Probabilistic timed automata are an extension of timed automata with discrete probability distributions. Simulation and bisimulation relations are widelystudied in the context of the analysis of system models, with applications in the stepwise development of systems and in model reduction ..."
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Cited by 2 (0 self)
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Abstract. Probabilistic timed automata are an extension of timed automata with discrete probability distributions. Simulation and bisimulation relations are widelystudied in the context of the analysis of system models, with applications in the stepwise development of systems and in model reduction. In this paper, we study probabilistic timed simulation and bisimulation relations for probabilistic timed automata. We present an EXPTIME algorithm for deciding whether two probabilistic timed automata are probabilistically timed similar or bisimilar. Furthermore, we consider a logical characterization of probabilistic timed bisimulation. 1
On the Steiner Tree 3/2Approximation For QuasiBipartite Graphs
, 1999
"... IR + be a nonnegative weighting of the edges of G. Assume V is partitioned as R X . A Steiner tree is any tree T of G such that every node in R is incident with at least one edge of T . The metric Steiner tree problem asks for a Steiner tree of minimum weight, given that w is a metric. When ..."
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Cited by 1 (0 self)
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IR + be a nonnegative weighting of the edges of G. Assume V is partitioned as R X . A Steiner tree is any tree T of G such that every node in R is incident with at least one edge of T . The metric Steiner tree problem asks for a Steiner tree of minimum weight, given that w is a metric. When X is a stable set of G, then (G, R, X) is called quasibipartite.
Timed Automata for the Development of RealTime Systems
, 2011
"... Timed automata are a popular formalism to model realtime systems. They were introduced two decades ago to support formal verification. Since then they have also been used for other purposes and a large has been introduced to be able to deal with the many different kinds of requirements of realtime ..."
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Timed automata are a popular formalism to model realtime systems. They were introduced two decades ago to support formal verification. Since then they have also been used for other purposes and a large has been introduced to be able to deal with the many different kinds of requirements of realtime system. This paper presents a fairly comprehensive survey, comprised of eighty variants of timed automata. The paper classifies all these eighty variants of timed automata in an effort to determine current developments. It uses analysis techniques, formal properties, and decision problems to draw distinctions between different versions. Moreover, the paper discusses the challenges behind using a timed automata specification to derive an implementation of a working realtime system and presents some solutions. Finally, the paper lists and classifies forty tools supporting timed automata. The paper does not only discuss many variants and their supporting concepts (e.g., closure properties, decision problems), techniques (e.g., for analysis), and tools, but it also attempts to help the reader navigate the vast literature in the field, to highlight differences and similarities between variants, and to reveal research trends and promising avenues for future exploration.
The Complexity of Codiagnosability for Discrete Event and Timed Systems
"... Abstract. In this paper we study the fault codiagnosis problem for discrete event systems given by finite automata (FA) and timed systems given by timed automata (TA). We provide a uniform characterization of codiagnosability for FA and TA which extends the necessary and sufficient condition that ch ..."
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Abstract. In this paper we study the fault codiagnosis problem for discrete event systems given by finite automata (FA) and timed systems given by timed automata (TA). We provide a uniform characterization of codiagnosability for FA and TA which extends the necessary and sufficient condition that characterizes diagnosability. We also settle the complexity of the codiagnosability problems both for FA and TA and show that codiagnosability is PSPACEcomplete in both cases. For FA this improves on the previously known bound (EXPTIME) and for TA it is a new result. Finally we address the codiagnosis problem for TA under bounded resources and show it is 2EXPTIMEcomplete. 1