Efficient state space search for time petri nets (1999)

by Johan Lilius
Venue:Electronic Notes in Theoretical Computer Science
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Structural Translation from Time Petri Nets to Timed Automata -- Model-Checking Time Petri Nets via Timed Automata

by Franck Cassez, Olivier H. Roux - JOURNAL OF SOFTWARE AND SYSTEMS , 2006
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Abstract - Cited by 39 (13 self) - Add to MetaCart
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Time Petri nets with inhibitor hyperarcs: formal semantics and state space computation

by Olivier (h. Roux, Didier Lime - Proceedings of the 25th International Conference on Applications and Theory of Petri Nets , 2004
"... Abstract. In this paper, we define Time Petri Nets with Inhibitor Hy-perarcs (IHTPN) as an extension of T-time Petri nets where time is associated with transitions. In this model, we consider stopwatches as-sociated with transitions which can be reset, stopped and started by using classical arcs and ..."
Abstract - Cited by 21 (4 self) - Add to MetaCart
Abstract. In this paper, we define Time Petri Nets with Inhibitor Hy-perarcs (IHTPN) as an extension of T-time Petri nets where time is associated with transitions. In this model, we consider stopwatches as-sociated with transitions which can be reset, stopped and started by using classical arcs and branch inhibitor hyperarcs introduced by Jan-icki and Koutny [1]. We give a formal semantics for IHTPNs in terms of Timed Transition Systems and we position IHTPNs with regard to other classes of Petri nets. We provide a method for computing the state space of IHTPNs. We first propose an exact computation using a gen-eral polyhedron representation of time constraints, then we propose an overapproximation of the polyhedra to allow a more efficient compact abstract representations of the state space based on DBM (Difference
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Comparison of Different Semantics for Time Petri Nets

by B. Bérard, F. Cassez, S. Haddad, Didier Lime, O. H. Roux - of LNCS , 2005
"... Abstract. In this paper we study the model of Time Petri Nets (TPNs) where a time interval is associated with the firing of a transition, but we extend it by considering general intervals rather than closed ones. A key feature of timed models is the memory policy, i.e. which timing informations are ..."
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Abstract. In this paper we study the model of Time Petri Nets (TPNs) where a time interval is associated with the firing of a transition, but we extend it by considering general intervals rather than closed ones. A key feature of timed models is the memory policy, i.e. which timing informations are kept when a transition is fired. The original model selects an intermediate semantics where the transitions disabled after consuming the tokens, as well as the firing transition, are reinitialised. However this semantics is not appropriate for some applications. So we consider here two alternative semantics: the atomic and the persistent atomic ones. First we present relevant patterns of discrete event systems which show the interest of these semantics. Then we compare the expressiveness of the three semantics w.r.t. the weak time bisimilarity establishing inclusion results in the general case. Furthermore we show that some inclusions are strict with unrestricted intervals even when nets are bounded. Then we focus on bounded TPNs with upper-closed intervals and we prove that the semantics are equivalent. Finally taking into account both the practical and the theoretical issues, we conclude that persistent atomic semantics should be preferred.
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Partial Order reduction for Model Checking of Timed Automata

by Marius Minea , 1999
"... Abstract. The paper presents a partial order reduction method applicable to networks of timed automata. The advantage of the method is that it reduces both the number of explored control states and the number of generated time zones. The approach is based on a local-time semantics for networks of ti ..."
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Abstract. The paper presents a partial order reduction method applicable to networks of timed automata. The advantage of the method is that it reduces both the number of explored control states and the number of generated time zones. The approach is based on a local-time semantics for networks of timed automata defined by Bengtsson et al. [1998], and used originally for local reachability analysis. In this semantics, each component automaton executes asynchronously, in its own local time scale, which is tracked by an auxiliary reference clock. On communication transitions, the automata synchronize their time scales. We show how this model can be used to perform model checking for an extension of linear temporal logic, which can express timing relations between events. We also show how for a class of timed automata, the local-time model can be implemented using difference bound matrices without any space penalty, despite the need to represent local time. Furthermore, we analyze the dependence relation between transitions in the new model and give practical conditions for selecting a reduced set of transitions. 1
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Complete finite prefixes of symbolic unfoldings of safe time Petri nets

by Thomas Chatain, Claude Jard - In ICATPN, volume 4024 of LNCS , 2006
"... Abstract. Monitoring real-time concurrent systems is a challenging task. In this paper we formulate (model-based) supervision by means of hidden state history reconstruction, from event (e.g. alarm) observations. We follow a so-called true concurrency approach using time Petri nets: the model define ..."
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Abstract. Monitoring real-time concurrent systems is a challenging task. In this paper we formulate (model-based) supervision by means of hidden state history reconstruction, from event (e.g. alarm) observations. We follow a so-called true concurrency approach using time Petri nets: the model defines explicitly the causal and concurrency relations between the observable events, produced by the system under supervision on different points of observation, and constrained by time aspects. The problem is to compute on-the-fly the different partial order histories, which are the possible explanations of the observable events. We do not impose that time is observable: the aim of supervision is to infer the partial ordering of the events and their possible firing dates. This is achieved by considering a model of the system under supervision, given as a time Petri net, and the on-the-fly construction of an unfolding, guided by the observations. Using a symbolic representation, this paper presents a new definition of the unfolding of time Petri nets with dense time.
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Timed unfoldings for networks of timed automata

by Patricia Bouyer, Serge Haddad, Pierre-alain Reynier - Research Rep. LSV-06-09, Lab. Spécification et Vérification, ENS de , 2006
"... Abstract. Whereas partial order methods have proved their efficiency for the analysis of discrete-event systems, their application to timed systems remains a challenging research topic. Here, we design a verification algorithm for networks of timed automata with invariants. Based on the unfolding te ..."
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Abstract. Whereas partial order methods have proved their efficiency for the analysis of discrete-event systems, their application to timed systems remains a challenging research topic. Here, we design a verification algorithm for networks of timed automata with invariants. Based on the unfolding technique, our method produces a branching process as an acyclic Petri net extended with read arcs. These arcs verify conditions on tokens without consuming them, thus expressing concurrency between conditions checks. They are useful for avoiding the explosion of the size of the unfolding due to clocks which are compared with constants but not reset. Furthermore, we attach zones to events, in addition to markings. We then compute a complete finite prefix of the unfolding. The presence of invariants goes against the concurrency since it entails a global synchronization on time. The use of read arcs and the analysis of the clock constraints appearing in invariants helps increasing the concurrency relation between events. Finally, the finite prefix can be used to decide reachability properties, and transition enabling. 1
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Abstractions and Partial Order Reductions for Checking Branching Properties of Time Petri Nets

by Wojciech Penczek, Agata Polrola , 2001
"... The paper deals with verification of untimed branching time properties of Time Petri Nets. The atomic variant of the geometric region method for preserving properties of CTL and ACTL is improved. Then, it is shown, for the first time, how to apply the partial order reduction method to deal with next ..."
Abstract - Cited by 9 (3 self) - Add to MetaCart
The paper deals with verification of untimed branching time properties of Time Petri Nets. The atomic variant of the geometric region method for preserving properties of CTL and ACTL is improved. Then, it is shown, for the first time, how to apply the partial order reduction method to deal with next-time free branching properties of Time Petri Nets. The above two results are combined offering an efficient method for model checking of ACTL X and CTL X properties of Time Petri Nets.

Model Checking of Time Petri Nets Based on Partial Order Semantics

by Burkhard Bieber, Hans Fleischhack , 1999
"... Model checking of place/transition-nets based on partial order semantics has been applied successfully to the analysis of causal behaviour of distributed systems. Here, this approach is extended to the causal behaviour of time Petri nets. Expansion of a time Petri net to an equivalent P/T-net is def ..."
Abstract - Cited by 8 (0 self) - Add to MetaCart
Model checking of place/transition-nets based on partial order semantics has been applied successfully to the analysis of causal behaviour of distributed systems. Here, this approach is extended to the causal behaviour of time Petri nets. Expansion of a time Petri net to an equivalent P/T-net is defined, and it is shown that (an abstraction of) the McMillan unfolding of the expanded net is sufficient for model checking w.r.t. formulae of a simple branching time temporal logic L.

Towards Bounded Model Checking for the Universal Fragment of TCTL

by Wojciech Penczek, Bozena Wozna, Andrzej Zbrzezny , 2002
"... Bounded Model Checking (BMC) based on SAT methods consists in searching for a counterexample of a particular length and to generate a propositional formula that is satis able i such a counterexample exists. Our paper shows how the concept of bounded model checking can be extended to deal with T ..."
Abstract - Cited by 8 (6 self) - Add to MetaCart
Bounded Model Checking (BMC) based on SAT methods consists in searching for a counterexample of a particular length and to generate a propositional formula that is satis able i such a counterexample exists. Our paper shows how the concept of bounded model checking can be extended to deal with TACTL (the universal fragment of TCTL) properties of Timed Automata.

Computing a Finite Prefix of a Time Petri Net

by Hans Fleischhack, Christian Stehno , 2001
"... Recently, model checking of Petri nets based on partial order semantics w.r.t. temporal logic formulae has been extended to time Petri nets. In this paper, we present an improved algorithm for computing the McMillan-unfolding of a time Petri net which gives a nite representation of the partial ..."
Abstract - Cited by 7 (1 self) - Add to MetaCart
Recently, model checking of Petri nets based on partial order semantics w.r.t. temporal logic formulae has been extended to time Petri nets. In this paper, we present an improved algorithm for computing the McMillan-unfolding of a time Petri net which gives a nite representation of the partial order semantics and some experimental results of its implementation within the PEP tool.