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56
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 show ..."
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Cited by 193 (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.
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 the v ..."
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Cited by 82 (7 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...
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 71 (17 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...
Model Checking Lossy Vector Addition Systems
 In STACS
, 1999
"... Lossy VASS (vector addition systems with states) are defined as a subclass of VASS in analogy to lossy FIFOchannel systems. They can be used to model concurrent systems with unreliable communication. We analyze the decidability of model checking problems for lossy systems and several branching ..."
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Cited by 43 (8 self)
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Lossy VASS (vector addition systems with states) are defined as a subclass of VASS in analogy to lossy FIFOchannel systems. They can be used to model concurrent systems with unreliable communication. We analyze the decidability of model checking problems for lossy systems and several branchingtime and lineartime temporal logics. We present an almost complete picture of the decidability of model checking for normal VASS, lossy VASS and lossy VASS with test for zero. 1 Introduction Systems are usually modeled by finite control transition systems with different kinds of variables and data structures like counters, clocks, stacks, fifochannels, etc. One of the widely used models of concurrent systems is the model of Petri nets which is equivalent to the model of vector addition systems with states (VASS for short). These models can be considered as particular cases of counter machines where tests to zero are forbidden (the addition of inhibitor arcs gives them the full power o...
Undecidable Problems in Unreliable Computations
 THEORETICAL COMPUTER SCIENCE
, 2000
"... Lossy counter machines are defined as Minsky ncounter machines where the values in the counters can spontaneously decrease at any time. While termination is decidable for lossy counter machines, structural termination (termination for every input) is undecidable. This undecidability result has f ..."
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Cited by 43 (2 self)
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Lossy counter machines are defined as Minsky ncounter machines where the values in the counters can spontaneously decrease at any time. While termination is decidable for lossy counter machines, structural termination (termination for every input) is undecidable. This undecidability result has far reaching consequences. Lossy counter machines can be used as a general tool to prove the undecidability of many problems, for example (1) The verification of systems that model communication through unreliable channels (e.g. model checking lossy fifochannel systems and lossy vector addition systems). (2) Several problems for reset Petri nets, like structural termination, boundedness and structural boundedness. (3) Parameterized problems like fairness of broadcast communication protocols.
Symbolic Verification of Lossy Channel Systems: Application to the Bounded Retransmission Protocol
 In TACAS'99. LNCS 1579
, 1999
"... We consider the problem of verifying automatically infinitestate systems that are systems of finite machines that communicate by exchanging messages through unbounded lossy fifo channels. In a previous work [1], we proposed an algorithmic approach based on constructing a symbolic representation ..."
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Cited by 36 (5 self)
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We consider the problem of verifying automatically infinitestate systems that are systems of finite machines that communicate by exchanging messages through unbounded lossy fifo channels. In a previous work [1], we proposed an algorithmic approach based on constructing a symbolic representation of the set of reachable configurations of a system by means of a class of regular expressions (SREs). The construction of such a representation consists of an iterative computation with an acceleration technique which enhance the chance of convergence. This technique is based on the analysis of the effect of iterating control loops. In the work we present here, we experiment our approach and show how it can be effectively applied. For that, we developed a tool prototype based on the results in [1]. Using this tool, we provide a fully automatic verification of (the parameterized version of) the Bounded Retransmission Protocol, for arbitrary values of the size of the transmitted files, and the allowed number of retransmissions. ? Contact author. 1 1
Using Forward Reachability Analysis for Verification of Lossy Channel Systems
 Formal Methods in System Design
, 2004
"... 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 protoco ..."
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Cited by 30 (4 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 straightforwardly construct an algorithm which explores the set of reachable states of a protocol, in order t...
Probabilistic Lossy Channel Systems
, 1996
"... Consider a system of finite state machines communicating with each other over unbounded FIFO buffers. Such a model of computation is, clearly, turing powerful. This model has been used as the backbone of ISO protocol specification languages Estelle and SDL, as it allows one to abstract away from ..."
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Cited by 25 (2 self)
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Consider a system of finite state machines communicating with each other over unbounded FIFO buffers. Such a model of computation is, clearly, turing powerful. This model has been used as the backbone of ISO protocol specification languages Estelle and SDL, as it allows one to abstract away from the details, such as errors in communication, that occur at lower levels of the protocol stack. It has recently been shown (in the literature) that realistic models which implicitly model errors in the communication buffers are more tractable than models which assume perfect communication. In this paper, we propose to make the model more realistic by modeling the probability of loss in the buffers. Given specifications in such a model we provide algorithms for the probabilistic reachability problem and the probabilistic modelchecking (against lineartime PTL requirements) problem.
Establishing Qualitative Properties for Probabilistic Lossy Channel Systems: an Algorithmic Approach
 In Proceedings of 5th International AMAST Workshop on RealTime and Probabilistic Systems (ARTS’99
, 1999
"... . Lossy channel systems (LCSs) are models for communicating systems where the subprocesses are linked via unbounded FIFO channels which might lose messages. Link protocols, such as the Alternating Bit Protocol and HDLC can be modelled with these systems. The decidability of several verification ..."
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Cited by 23 (5 self)
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. Lossy channel systems (LCSs) are models for communicating systems where the subprocesses are linked via unbounded FIFO channels which might lose messages. Link protocols, such as the Alternating Bit Protocol and HDLC can be modelled with these systems. The decidability of several verification problems of LCSs has been investigated by Abdulla & Jonsson [AJ93,AJ94], e.g. they have shown that the reachability problem for LCSs is decidable while LTL model checking is not. In this paper, we consider probabilistic LCSs (which are LCSs where the transitions are augmented with appropriate probabilities) as introduced by [IN97] and show that the question of whether or not a linear time property holds with probability 1 is decidable. More precisely, we show how LTL nX model checking for (certain types of) probabilistic LCSs can be reduced to a reachability problem in a (nonprobabilistic) LCS where the latter can be solved with the methods of [AJ93]. 1 1 Introduction Traditiona...
Verification of probabilistic systems with faulty communication
 IN PROCEEDINGS OF FOSSACS 2003
, 2003
"... ..."