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217
WellStructured Transition Systems Everywhere!
 THEORETICAL COMPUTER SCIENCE
, 1998
"... Wellstructured transition systems (WSTS's) are a general class of infinite state systems for which decidability results rely on the existence of a wellquasiordering between states that is compatible with the transitions. In this article, we provide an extensive treatment of the WSTS idea and ..."
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Cited by 258 (9 self)
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Wellstructured transition systems (WSTS's) are a general class of infinite state systems for which decidability results rely on the existence of a wellquasiordering between states that is compatible with the transitions. In this article, we provide an extensive treatment of the WSTS idea and show several new results. Our improved definitions allow many examples of classical systems to be seen as instances of WSTS's.
General Decidability Theorems for InfiniteState Systems
, 1996
"... ) Parosh Aziz Abdulla Uppsala University K¯arlis Cer¯ans University of Latvia Bengt Jonsson Uppsala University YihKuen Tsay National Taiwan University Abstract Over the last few years there has been an increasing research effort directed towards the automatic verification of infinite state sys ..."
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Cited by 140 (19 self)
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) Parosh Aziz Abdulla Uppsala University K¯arlis Cer¯ans University of Latvia Bengt Jonsson Uppsala University YihKuen Tsay National Taiwan University Abstract Over the last few years there has been an increasing research effort directed towards the automatic verification of infinite state systems. For different classes of such systems (e.g., hybrid automata, dataindependent systems, relational automata, Petri nets, and lossy channel systems) this research has resulted in numerous highly nontrivial algorithms. As the interest in this area increases, it will be important to extract common principles that underly these and related results. This paper is concerned with identifying general mathematical structures which could serve as sufficient conditions for achieving decidability. We present decidability results for systems which consist of a finite control part operating on an infinite data domain. The data domain is equipped with a wellordered and wellfounded preorder such tha...
Symbolic Verification of Communication Protocols with Infinite State Spaces using QDDs (Extended Abstract)
 In CAV'96. LNCS 1102
"... ) Bernard Boigelot Universit'e de Li`ege Institut Montefiore, B28 4000 Li`ege SartTilman, Belgium Email: boigelot@montefiore.ulg.ac.be Patrice Godefroid Lucent Technologies  Bell Laboratories 1000 E. Warrenville Road Naperville, IL 60566, U.S.A. Email: god@belllabs.com Abstract We study ..."
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Cited by 98 (8 self)
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) Bernard Boigelot Universit'e de Li`ege Institut Montefiore, B28 4000 Li`ege SartTilman, Belgium Email: boigelot@montefiore.ulg.ac.be Patrice Godefroid Lucent Technologies  Bell Laboratories 1000 E. Warrenville Road Naperville, IL 60566, U.S.A. Email: god@belllabs.com Abstract We study the verification of properties of communication protocols modeled by a finite set of finitestate machines that communicate by exchanging messages via unbounded FIFO queues. It is wellknown that most interesting verification problems, such as deadlock detection, are undecidable for this class of systems. However, in practice, these verification problems may very well turn out to be decidable for a subclass containing most "real" protocols. Motivated by this optimistic (and, we claim, realistic) observation, we present an algorithm that may construct a finite and exact representation of the state space of a communication protocol, even if this state space is infinite. Our algorithm performs a loo...
Conversation Protocols: A Formalism for Specification and Verification of Reactive Electronic Services
 In Proc. Int. Conf. on Implementation and Application of Automata (CIAA
, 2004
"... This paper focuses on the realizability problem of a framework for modeling and specifying the global behaviors of reactive electronic services (eservices). In this framework, Web accessible programs (peers) communicate by asynchronous message passing, and a virtual global watcher silently listens ..."
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Cited by 88 (20 self)
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This paper focuses on the realizability problem of a framework for modeling and specifying the global behaviors of reactive electronic services (eservices). In this framework, Web accessible programs (peers) communicate by asynchronous message passing, and a virtual global watcher silently listens to the network. The global behavior is characterized by a "conversation", which is the infinite sequence of messages observed by the watcher. We show that given a Buchi automaton specifying the desired set of conversations, called a "conversation protocol", it is possible to realize the protocol using a set of finite state peers if three realizability conditions are satisfied. In particular, the synthesized peers will conform to the protocol by generating only those conversations specified by the protocol. Our results enable a topdown verification strategy where (1) A conversation protocol is specified by a realizable Buchi automaton, (2) The properties of the protocol are verified on the Buchi automaton specification, and (3) The peer implementations are synthesized from the protocol via projection.
OntheFly Analysis of Systems with Unbounded, Lossy FIFO Channels
 In CAV'98. LNCS 1427
, 1998
"... . We consider symbolic onthefly verification methods for systems of finitestate machines that communicate by exchanging messages via unbounded and lossy FIFO queues. We propose a novel representation formalism, called simple regular expressions (SREs), for representing sets of states of proto ..."
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Cited by 81 (19 self)
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. We consider symbolic onthefly verification methods for systems of finitestate machines that communicate by exchanging messages via unbounded and lossy FIFO queues. We propose a novel representation formalism, called simple regular expressions (SREs), for representing sets of states of protocols with lossy FIFO channels. We show that the class of languages representable by SREs is exactly the class of downward closed languages that arise in the analysis of such protocols. We give methods for (i) computing inclusion between SREs, (ii) an SRE representing the set of states reachable by executing a single transition in a system, and (iii) an SRE representing the set of states reachable by an arbitrary number of executions of a control loop of a program. All these operations are rather simple and can be carried out in polynomial time. With these techniques, one can construct a semialgorithm which explores the set of reachable states of a protocol, in order to check variou...
Algorithmic analysis of programs with well quasiordered domains
 Information and Computation
"... Over the past few years increasing research effort has been directed towards the automatic verification of infinitestate systems. This paper is concerned with identifying general mathematical structures which can serve as sufficient conditions for achieving decidability. We present decidability res ..."
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Cited by 74 (17 self)
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Over the past few years increasing research effort has been directed towards the automatic verification of infinitestate systems. This paper is concerned with identifying general mathematical structures which can serve as sufficient conditions for achieving decidability. We present decidability results for a class of systems (called wellstructured systems) which consist of a finite control part operating on an infinite data domain. The results assume that the data domain is equipped with a preorder which is a well quasiordering, such that the transition relation is ``monotonic' ' (a simulation) with respect to the preorder. We show that the following properties are decidable for wellstructured systems: v Reachability: whether a certain set of control states is reachable. Other safety properties can be reduced to the reachability problem. 1
How to compose PresburgerAccelerations: Applications to Broadcast Protocols
 IN PROC. 22ND CONF. FOUND. OF SOFTWARE TECHNOLOGY AND THEOR. COMP. SCI. (FST&TCS'2002), KANPUR
, 2002
"... Finite linear systems are finite sets of linear functions whose guards are de fined by Presburger formulas, and whose the squares matrice associated generate a finite multiplicative monoid. We prove that for finite linear systems, the accelerations of sequences of transitions always produce an effec ..."
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Cited by 70 (19 self)
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Finite linear systems are finite sets of linear functions whose guards are de fined by Presburger formulas, and whose the squares matrice associated generate a finite multiplicative monoid. We prove that for finite linear systems, the accelerations of sequences of transitions always produce an effective Presburgerdefinable relation. We then show how to choose the good sequences of length n whose number is polynomial in n although the total number of cycles of length n is exponential in n. We implement these theoretical results in the tool FAST [FAS] (Fast Acceleration of Symbolic Transition systems). FAST computes in few seconds the minimal deterministic finite automata that represent the reachability sets of 8 wellknown broadcast protocols.
Undecidable Verification Problems for Programs with Unreliable Channels
 Information and Computation
, 1994
"... We consider the verification of a particular class of infinitestate systems, namely systems consisting of finitestate processes that communicate via unbounded lossy FIFO channels. This class is able to model e.g. link protocols such as the Alternating Bit Protocol and HDLC. In an earlier paper, we ..."
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Cited by 67 (13 self)
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We consider the verification of a particular class of infinitestate systems, namely systems consisting of finitestate processes that communicate via unbounded lossy FIFO channels. This class is able to model e.g. link protocols such as the Alternating Bit Protocol and HDLC. In an earlier paper, we showed that the problems of checking reachability, safety properties, and eventuality properties are decidable for this class of systems. In this paper, we show that the following problems are undecidable, namely ffl The model checking problem in propositional temporal logics such as Propositional Linear Time Temporal Logic (PTL) and Computation Tree Logic (CTL). ffl The problem of deciding eventuality properties with fair channels: do all computations eventually reach a given set of states if the unreliable channels satisfy fairness assumptions. The results are obtained through a reduction from a variant of Post's Correspondence Problem. This research report is a revised and extended ...
Timed petri nets and BQOs
 In Proc. ICATPN’01
, 2001
"... Abstract. We consider (unbounded) Timed Petri Nets (TPNs) where each token is equipped with a realvalued clock representing the “age” of the token. Each arc in the net is provided with a subinterval of the natural numbers, restricting the ages of the tokens travelling the arc. We apply a methodolog ..."
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Cited by 63 (9 self)
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Abstract. We consider (unbounded) Timed Petri Nets (TPNs) where each token is equipped with a realvalued clock representing the “age” of the token. Each arc in the net is provided with a subinterval of the natural numbers, restricting the ages of the tokens travelling the arc. We apply a methodology developed in [AN00], based on the theory of better quasi orderings (BQOs), to derive an efficient constraint system for automatic verification of safety properties for TPNs. We have implemented a prototype based on our method and applied it for verification of a parametrized version of Fischer’s protocol. 1