On the power of synchronization between two adjacent processes

Chalopin, Jérémie; Métivier, Yves

doi:10.1007/s00446-010-0115-3

“…In these models of distributed computing, processes share a limited knowledge about the underlying communication graph and do not have unique identifiers. For instance, in [19], sufficient and sometimes necessary conditions on the communication graph and the initial, common knowledge are given for fundamental distributed problems such as leader election and enumeration [6,38,19]. (Interestingly, [19] is an introduction to local computation in anonymous networks.…”

Section: Introductionmentioning

confidence: 99%

The Universe of Symmetry Breaking Tasks

Imbs

¹

,

Rajsbaum²,

Raynal

³

2011

Structural Information and Communication Complexity

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Processes in a concurrent system need to coordinate using a shared memory or a message-passing subsystem in order to solve agreement tasks such as, for example, consensus or set agreement. However, often coordination is needed to "break the symmetry" of processes that are initially in the same state, for example, to get exclusive access to a shared resource, to get distinct names or to elect a leader.This paper introduces and studies the family of generalized symmetry breaking (GSB) tasks, that includes election, renaming and many other symmetry breaking tasks. Differently from agreement tasks, a GSB task is "inputless", in the sense that processes do not propose values; the task specifies only the symmetry breaking requirement, independently of the system's initial state (where processes differ only on their identifiers). Among many various characterizing the family of GSB tasks, it is shown that (non adaptive) perfect renaming is universal for all GSB tasks.Résumé : Dans un système réparti, les processus ont besoin de coordination en utilisant un sous-système de mémoire partagée ou de passage de message pour pouvoir résoudre des problèmes tels que le consensus ou l'accord ensembliste. Dans certains cas, la coordination est nécéssaire pour "casser la symétrie" entre des processus qui ont le mêmeétat initial.Ce rapport introduit la famille des tâches "generalized symmetry breaking" (GSB) qui inclut l'élection, le renommage et de nombreuses autres tâches qui cassent la symétrie.

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“…For instance, in [19], sufficient and sometimes necessary conditions on the communication graph and the initial, common knowledge are given for fundamental distributed problems such as leader election and enumeration [6,38,19]. (Interestingly, [19] is an introduction to local computation in anonymous networks. )…”

Section: Introductionmentioning

confidence: 99%

The universe of symmetry breaking tasks

Imbs

¹

,

Rajsbaum²,

Raynal

³

2011

Proceedings of the 30th Annual ACM SIGACT-SIGOPS Symposium on Principles of Distributed Computing

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Processes in a concurrent system need to coordinate using a shared memory or a message-passing subsystem in order to solve agreement tasks such as, for example, consensus or set agreement. However, often coordination is needed to "break the symmetry" of processes that are initially in the same state, for example, to get exclusive access to a shared resource, to get distinct names or to elect a leader.This paper introduces and studies the family of generalized symmetry breaking (GSB) tasks, that includes election, renaming and many other symmetry breaking tasks. Differently from agreement tasks, a GSB task is "inputless", in the sense that processes do not propose values; the task specifies only the symmetry breaking requirement, independently of the system's initial state (where processes differ only on their identifiers). Among many various characterizing the family of GSB tasks, it is shown that (non adaptive) perfect renaming is universal for all GSB tasks.Key-words: Agreement, Coordination, Decision task, Election, Disagreement, Distributed computability, Renaming, k-Set agreement, Symmetry Breaking, Universal construction, Wait-freedom. L'univers des tâches "Symmetry Breaking"Résumé : Dans un système réparti, les processus ont besoin de coordination en utilisant un sous-système de mémoire partagée ou de passage de message pour pouvoir résoudre des problèmes tels que le consensus ou l'accord ensembliste. Dans certains cas, la coordination est nécéssaire pour "casser la symétrie" entre des processus qui ont le mêmeétat initial.Ce rapport introduit la famille des tâches "generalized symmetry breaking" (GSB) qui inclut l'élection, le renommage et de nombreuses autres tâches qui cassent la symétrie. IntroductionProcesses of a distributed system need to coordinate through a communication medium (shared memory or message-passing subsystem) in order to solve various forms of agreement problems. If no coordination is ever needed in the computation, then we have a set of centralized, independent programs rather than a global distributed computation. Agreement coordination is one of the main issues of distributed computing. As an example, consensus is a very strong form of agreement where processes have to agree on the input of some process. It is a fundamental problem in distributed computing, and the cornerstone when one has to implement a replicated state machine, e.g. [20,37,40].Considering a shared memory asynchronous system where processes may fail by crashing, we are interested here in tasks [39], defined by an input/output relation ∆, and where processes start with private input values forming an input vector I and, after communication, individually decide on output values forming an output vector O, satisfying the specification of the considered task, i.e., O ∈ ∆(I). Several specific agreement tasks have been studied in detail, such as consensus [25] and set agreement [21]. Indeed, the importance of agreement is such that it has been studied deeply, from a more general perspective, defining familie...

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“…A characterization of graphs which admit an election algorithm by giving definition of coverings (for this model) and the corresponding election algorithm may be found in [8].…”

Section: The Family Of Trees or The Family Of Complete Graphsmentioning

confidence: 99%

“…-the model defined by Angluin in [1] (inspired by Milne and Milner's model for distributed systems [19]) and, more generally, the model of local computations on labelled edges [8]; -the model defined by Mazurkiewicz [18]; -asynchronous systems where processes communicate with synchronous message passing (i.e., there is a synchronization between the process sending the message and the one receiving it, it has been defined by Hoare in [13]). …”

Section: About Other Modelsmentioning

confidence: 99%

See 1 more Smart Citation

Election in partially anonymous networks with arbitrary knowledge in message passing systems

Chalopin

¹

,

Godard

²

,

Métivier

³

2012

Self Cite

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This paper attempts to find an answer to an open question of Angluin in her seminal paper (1980) about the election problem for families of graphs (Section 4, page 87). More precisely, we characterize families of (labelled) graphs which admit an election algorithm in the message passing model by using the notion of quasi-coverings which captures "the existence of large enough area of one graph that looks locally like another graph".

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On the power of synchronization between two adjacent processes

Cited by 8 publications

References 25 publications

The Universe of Symmetry Breaking Tasks

The Universe of Symmetry Breaking Tasks

The universe of symmetry breaking tasks

Election in partially anonymous networks with arbitrary knowledge in message passing systems

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