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Fair testing
 Concur ’95: Concurrency Theory, volume 962 of Lecture Notes in Computer Science
, 1995
"... In this paper we present a solution to the longstanding problem of characterising the coarsest livenesspreserving precongruence with respect to a full (TCSPinspired) process algebra. In fact, we present two distinct characterisations, which give rise to the same relation: an operational one base ..."
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Cited by 64 (0 self)
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In this paper we present a solution to the longstanding problem of characterising the coarsest livenesspreserving precongruence with respect to a full (TCSPinspired) process algebra. In fact, we present two distinct characterisations, which give rise to the same relation: an operational one based on a De NicolaHennessylike testing modality which we call shouldtesting, and a denotational one based on a refined notion of failures. One of the distinguishing characteristics of the shouldtesting precongruence is that it abstracts from divergences in the same way as Milner’s observation congruence, and as a consequence is strictly coarser than observation congruence. In other words, shouldtesting has a builtin fairness assumption. This is in itself a property long soughtafter; it is in notable contrast to the wellknown musttesting of De Nicola and Hennessy (denotationally characterised by a combination of failures and divergences), which treats divergence as catrastrophic and hence is incompatible with observation congruence. Due to these characteristics, shouldtesting supports modular reasoning and allows to use the proof techniques of observation congruence, but also supports additional laws and techniques.
Fair Simulation
 Information and Computation
, 1997
"... The simulation preorder for labeled transition systems is defined locally as a game that relates states with their immediate successor states. Simulation enjoys many appealing properties. First, simulation has a fully abstract semantics: system S simulates system I iff every computation tree embedd ..."
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Cited by 47 (17 self)
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The simulation preorder for labeled transition systems is defined locally as a game that relates states with their immediate successor states. Simulation enjoys many appealing properties. First, simulation has a fully abstract semantics: system S simulates system I iff every computation tree embedded in the unrolling of I can be embedded also in the unrolling of S. Second, simulation has a logical characterization: S simulates I iff every universal branchingtime formula satisfied by S is satisfied also by I. It follows that simulation is a suitable notion of implementation, and it is the coarsest abstraction of a system that preserves universal branchingtime properties. Third, based on its local definition, simulation between finitestate systems can be checked in polynomial time. Finally, simulation implies tracecontainment, which cannot be defined locally and requires polynomial space for verification. Hence simulation is widely used both in manual and in automatic verification. ...
Traces, pomsets, fairness and full abstraction for communicating processes
 Proc. CONCUR 2002, Brno. Springer LNCS
, 2002
"... Abstract. We provide a denotational trace semantics for processes with synchronous communication and a form of weakly fair parallelism. The semantics is fully abstract: processes have the same trace sets if and only if their communication behaviors are identical in all contexts. The model can easily ..."
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Cited by 7 (4 self)
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Abstract. We provide a denotational trace semantics for processes with synchronous communication and a form of weakly fair parallelism. The semantics is fully abstract: processes have the same trace sets if and only if their communication behaviors are identical in all contexts. The model can easily be adapted for asynchronously communicating processes, or for sharedmemory parallel programs. We also provide a partialorder semantics, using pomsets adapted for synchronization and our form of fairness. The pomset semantics can also be adjusted to model alternative paradigms. The traces of a process can be recovered from the pomset semantics by taking all fair interleavings consistent with the partial order. 1
Fair Bisimulation
 TACAS 00
, 2000
"... Bisimulations enjoy numerous applications in the analysis of labeled transition systems. Many of these applications are based on two central observations: first, bisimilar systems satisfy the same branchingtime properties; second, bisimilarity can be checked efficiently for finitestate systems. ..."
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Bisimulations enjoy numerous applications in the analysis of labeled transition systems. Many of these applications are based on two central observations: first, bisimilar systems satisfy the same branchingtime properties; second, bisimilarity can be checked efficiently for finitestate systems. The local character of bisimulation, however, makes it difficult to address liveness concerns. Indeed, the definitions of fair bisimulation that have been proposed in the literature sacrifice locality, and with it, also efficient checkability. We put forward a new definition of fair bisimulation which does not suffer from this drawback. The bisimilarity of
C.: Explicit fairness in testing semantics
 Logical Methods in Computer Science 5(2
, 2009
"... address: ..."
Liveness and fairness in processalgebraic verification
, 2003
"... Although liveness and fairness have been used for a long time in classical model checking, with processalgebraic methods they have seen far less use. One problem is combining fairness with the compositionality of process algebra. In this article we analyse this problem, and then present an approac ..."
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Cited by 4 (0 self)
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Although liveness and fairness have been used for a long time in classical model checking, with processalgebraic methods they have seen far less use. One problem is combining fairness with the compositionality of process algebra. In this article we analyse this problem, and then present an approach for using a class of fairness constraints. The approach fulfills all the requirements of compositionality and is compatible with an existing semantics. It is based on the standard LTS model and does not require new fairnessrelated constructs or rules for the process algebra. Therefore, it avoids potential conflicts between the fairness requirements and the underlying transition system. Although adding fairness can create an infinite subsystem, a larger system in which the subsystem is placed can still be finite. We present an algorithm for constructing a finite LTS which is equivalent to the larger system in every case that an exact finite representation exists, and which otherwise is a conservative estimate of it. However, checking whether an exact finite representation exists is costlier than building the representation, namely, it is PSPACEcomplete in the size of an intermediate parameter system.
Semantics for Finite Delay
 Theoretical Computer Science
, 1997
"... We produce a fully abstract model for a notion of process equivalence taking into account issues of fairness, called by Milner fair bisimilarity. The model uses Aczel's antifoundation axiom and it is constructed along the lines of the antifounded model for SCCS given by Aczel. We revisit Acze ..."
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Cited by 4 (2 self)
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We produce a fully abstract model for a notion of process equivalence taking into account issues of fairness, called by Milner fair bisimilarity. The model uses Aczel's antifoundation axiom and it is constructed along the lines of the antifounded model for SCCS given by Aczel. We revisit Aczel's semantics for SCCS where we prove a unique fixpoint theorem under the assumption of guarded recursion. Then we consider Milner's extension of SCCS to include a finite delay operator ". Working with fair bisimilarity we construct a fully abstract model, which is also fully abstract for fortification. We discuss the solution of recursive equations in the model. The paper is concluded with an investigation of the algebraic theory of fair bisimilarity. Keywords: fairness, antifoundation, finite delay, parallelism, fair bisimilarity, fortification. This paper was composed while I was unemployed and an unofficial visitor at the Department of Mathematics, University of Ioannina, Greece. My than...
The Semantics Of Fair Recursion With Divergence
, 1996
"... We recast Milner's work on SCCSffl, a calculus for finite but unbounded delay based on SCCS, by giving a denotational semantics for admissibility of infinite computations on a bifinite domain K. Using Abramsky's SFP domain D for bisimulation we obtain a fully abstract model in D \Theta K f ..."
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Cited by 3 (1 self)
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We recast Milner's work on SCCSffl, a calculus for finite but unbounded delay based on SCCS, by giving a denotational semantics for admissibility of infinite computations on a bifinite domain K. Using Abramsky's SFP domain D for bisimulation we obtain a fully abstract model in D \Theta K for an operational preorder which generalizes Milner's fortification. Our preorder includes divergence and its restriction to finite behavior corresponds to Abramsky's finitary preorder. By virtue of bifiniteness of D \Theta K we obtain a Stone dual at the level of objects. Since Milner's delay operators ffl and ffi turn out to correspond to the greatest, respectively least, fixed point on K, we consequently enrich SCCS with an additional recursive binding modeled as the greatest fixed point. For the body 1x + p, the new recursive binding imposes finite delay, whereas the ordinary recursion admits infinite, as well as finite, delay of p. We define a notion of admissibility and a denotational semantics...
The Semantics of Triveni: A ProcessAlgebraic API for Threads + Events
, 1998
"... This paper describes compositional semantics (operational, denotational and logical) for a process algebra enhanced with input/output actions and preemption combinators, in the presence of fairness. The context of this paper is Triveni, a processalgebrabased design methodology that combines thread ..."
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Cited by 2 (1 self)
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This paper describes compositional semantics (operational, denotational and logical) for a process algebra enhanced with input/output actions and preemption combinators, in the presence of fairness. The context of this paper is Triveni, a processalgebrabased design methodology that combines threads and events in the context of objectoriented programming [CJJ
Fair Testing Through Probabilistic Testing
, 1999
"... In this paper we define a probabilistic testing semantics which can be used to alternatively characterize fair testing. The key idea is to define a probabilistic semantics in such a way that two nonprobabilistic processes are fair equivalent iff any probabilistic version of both processes are equiv ..."
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In this paper we define a probabilistic testing semantics which can be used to alternatively characterize fair testing. The key idea is to define a probabilistic semantics in such a way that two nonprobabilistic processes are fair equivalent iff any probabilistic version of both processes are equivalent in our probabilistic testing semantics. In order to get this result we define a simple probabilistic must semantics by saying that a probabilistic process must pass a test iff the probability with which the process passes the test equals 1. Finally, we present an algorithm for deciding whether the probability with which a finitestate process passes a finitestate test equals 1. Alternatively, this algorithm can be used for computing whether a finitestate process fairly passes a finitestate test. Keywords: Testing semantics, fair testing, probabilistic processes. 1. INTRODUCTION Formal models of concurrency have been proved to be very useful to properly specify concurrent and distr...