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29
On the Cost of FaultTolerant Consensus When There Are No Faults  A Tutorial
, 2001
"... We consider the consensus problem in asynchronous models enriched with unreliable failure detectors or partial synchrony, where processes can crash or links may fail by losing messages. ..."
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Cited by 68 (8 self)
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We consider the consensus problem in asynchronous models enriched with unreliable failure detectors or partial synchrony, where processes can crash or links may fail by losing messages.
Roundbyround fault detectors: Unifying synchrony and asynchrony
 In Proc of the 17th ACM Symp. Principles of Distributed Computing (PODC
, 1998
"... and insights. 1 Introduction For many years, researchers studying synchronous messagepassing systems have considered algorithms composed of rounds of computation. In each round, a process sends a message to the others and then waits to receive messages from the other processes. The synchronous natu ..."
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Cited by 54 (9 self)
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and insights. 1 Introduction For many years, researchers studying synchronous messagepassing systems have considered algorithms composed of rounds of computation. In each round, a process sends a message to the others and then waits to receive messages from the other processes. The synchronous nature of the system ensures that, by the end of the round, each process receives all messages sent to it in that round by correct processes. In the parlance of Elrad and Frances [1] then, each round of a synchronous system is a communicationclosedlayer.
Hundreds of Impossibility Results for Distributed Computing
 Distributed Computing
, 2003
"... We survey results from distributed computing that show tasks to be impossible, either outright or within given resource bounds, in various models. The parameters of the models considered include synchrony, faulttolerance, different communication media, and randomization. The resource bounds refe ..."
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Cited by 52 (5 self)
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We survey results from distributed computing that show tasks to be impossible, either outright or within given resource bounds, in various models. The parameters of the models considered include synchrony, faulttolerance, different communication media, and randomization. The resource bounds refer to time, space and message complexity. These results are useful in understanding the inherent difficulty of individual problems and in studying the power of different models of distributed computing.
Algebraic spans
, 2000
"... Topological methods have yielded a variety of lower bounds and impossibility results for distributed computing. In this paper, we introduce a new tool for proving impossibility results, which is based on a core theorem of algebraic topology, the acyclic carrier theorem, and unifies, generalizes and ..."
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Cited by 35 (17 self)
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Topological methods have yielded a variety of lower bounds and impossibility results for distributed computing. In this paper, we introduce a new tool for proving impossibility results, which is based on a core theorem of algebraic topology, the acyclic carrier theorem, and unifies, generalizes and extends earlier results.
Tight bounds for kset agreement with limited scope accuracy failure detectors
 Distributed Computing
"... In a system with limitedscope failure detectors, there are q clusters of processes such that some correct process in each cluster is never suspected by any process in that cluster. The failure detector class Sx,q satisfies this property all the time, while ⋄Sx,q satisfies it eventually. This paper ..."
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Cited by 13 (1 self)
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In a system with limitedscope failure detectors, there are q clusters of processes such that some correct process in each cluster is never suspected by any process in that cluster. The failure detector class Sx,q satisfies this property all the time, while ⋄Sx,q satisfies it eventually. This paper gives the first tight bounds for the kset agreement task in asynchronous messagepassing models augmented with failure detectors from either the Sx,q or ⋄Sx,q classes. For Sx,q, we show that any kset agreement protocol that tolerates f failures must satisfy f<k+ x − q, wherexisthe combined size of the k largest clusters. This result establishes for the first time that the protocol of Mostéfaoui and Raynal for the Sx = Sx,1 failure detector is optimal. For ⋄Sx,q, we show that any kset agreement protocol that tolerates f failures must satisfy f<min ( n+1,k+ x − q). We give a novel protocol 2 that matches our lower bound, disproving a conjecture of Mostéfaoui and Raynal for the ⋄Sx = ⋄Sx,1 failure detector. Our lower bounds exploit techniques borrowed from Combinatorial Topology, demonstrating for the first time that this approach is applicable to models that encompass failure detectors. 1
Time Bounds for Decision Problems in the Presence of Timing Uncertainty and Failures
 Journal of Parallel and Distributed Computing
, 1993
"... This paper studies the time complexity of solving decision problems in ..."
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Cited by 11 (2 self)
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This paper studies the time complexity of solving decision problems in
The Iterated Restricted Immediate Snapshot Model
, 2008
"... In the Iterated Immediate Snapshot model (IIS) the memory consists of a sequence of oneshot Immediate Snapshot (IS) objects. Processes access the sequence of IS objects, onebyone, asynchronously, in a waitfree manner; any number of processes can crash. Its interest lies in the elegant recursive ..."
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Cited by 10 (3 self)
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In the Iterated Immediate Snapshot model (IIS) the memory consists of a sequence of oneshot Immediate Snapshot (IS) objects. Processes access the sequence of IS objects, onebyone, asynchronously, in a waitfree manner; any number of processes can crash. Its interest lies in the elegant recursive structure of its runs, hence of the ease to analyze it round by round. In a very interesting way, Borowsky and Gafni have shown that the IIS model and the read/write model are equivalent for the waitfree solvability of decision tasks. This paper extends the benefits of the IIS model to partially synchronous systems. Given a shared memory model enriched with a failure detector, what is an equivalent IIS model? The paper shows that an elegant way of capturing the power of a failure detector and other partially synchronous systems in the IIS model is by restricting appropriately its set of runs, giving rise to the Iterated Restricted Immediate Snapshot model (IRIS).
Towards a topological characterization of asynchronous complexity
 In Proceedings of the 16th Annual ACM Symposium on Principles of Distributed Computing
, 1997
"... Abstract. This paper introduces the use of topological models and methods, formerly used to analyze computability, as tools for the quantification and classification of asynchronous complexity. We present the first asynchronous complexity theorem, applied to decision tasks in the iterated immediate ..."
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Cited by 9 (0 self)
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Abstract. This paper introduces the use of topological models and methods, formerly used to analyze computability, as tools for the quantification and classification of asynchronous complexity. We present the first asynchronous complexity theorem, applied to decision tasks in the iterated immediate snapshot (IIS) model of Borowsky and Gafni. We do so by introducing a novel form of topological tool called the nonuniform chromatic subdivision. Building on the framework of Herlihy and Shavit’s topological computability model, our theorem states that the time complexity of any asynchronous algorithm is directly proportional to the level of nonuniform chromatic subdivisions necessary to allow a simplicial map from a task’s input complex to its output complex. To show the power of our theorem, we use it to derive a new tight bound on the time to achieve n process approximate agreement in the IIS model: � max input−min input � logd, where d = 3 for two processes ɛ and d = 2 for three or more. This closes an intriguing gap between the known upper and lower bounds implied by the work of Aspnes and Herlihy. More than the new bounds themselves, the importance of our asynchronous complexity theorem is that the algorithms and lower bounds it allows us to derive are intuitive and simple, with topological proofs that require no mention of concurrency at all.
The unified structure of consensus: a layered analysis approach
 In Proceedings of the Seventeenth ACM Symposium on Principles of Distributed Computing [1
"... We introduce a simple notion of layering that provides a tool for defining submodels of a given model of distributed computation. We describe two layerings, the synchronic and the permutation layering, and show that they induce appropriate submodels of several asynchronous models of computation. The ..."
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Cited by 8 (3 self)
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We introduce a simple notion of layering that provides a tool for defining submodels of a given model of distributed computation. We describe two layerings, the synchronic and the permutation layering, and show that they induce appropriate submodels of several asynchronous models of computation. The synchronic layering applies to the synchronous model too. We perform a modelindependent analysis of the consensus problem in terms of abstract connectivity properties of layering functions. By defining particular layerings in specific models, we derive several popular (and some new) lower bounds and impossibility results for consensus in various classical models. These results are often stronger in the sense that they apply to the subrnodel induced by the layering. The proofs obtained in this way are also simpler and more direct than existing ones. Moreover, the analysis is done in a uniform fashion and demonstrates the fundamental common structure of the consensus problem in the presence of failures. The analysis is then extended to general decision problems (lresilient in the asynchronous models, trounds in the tresilient synchronous model), providing a characterization of solvability of decision problems in the style of [8] which, for some of the models, is given for the first time. 1 introduction For almost two decades now, the consensus problem has played a central role in the study of faulttolerant distributed
Lower Bounds in Distributed Computing
, 2000
"... This paper discusses results that say what cannot be computed in certain environments or when insucient resources are available. A comprehensive survey would require an entire book. As in Nancy Lynch's excellent 1989 paper, \A Hundred Impossibility Proofs for Distributed Computing" [86], w ..."
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Cited by 7 (1 self)
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This paper discusses results that say what cannot be computed in certain environments or when insucient resources are available. A comprehensive survey would require an entire book. As in Nancy Lynch's excellent 1989 paper, \A Hundred Impossibility Proofs for Distributed Computing" [86], we shall restrict ourselves to some of the results we like best or think are most important. Our aim is to give you the avour of the results and some of the techniques that have been used. We shall also mention some interesting open problems and provide an extensive list of references. The focus will be on results from the past decade.