8 Search Results for "Imbs, Damien"

Document
DOI: 10.4230/LIPIcs.OPODIS.2025.5
Tight Conditions for Binary-Output Tasks Under Crashes

Authors: Timothé Albouy, Antonio Fernández Anta, Chryssis Georgiou, Nicolas Nicolaou, and Junlang Wang

Published in: LIPIcs, Volume 361, 29th International Conference on Principles of Distributed Systems (OPODIS 2025)

Abstract
This paper explores necessary and sufficient system conditions to solve distributed tasks with binary outputs (i.e., tasks with output values in {0,1}). We focus on the distinct output sets of values a task can produce (intentionally disregarding validity and value multiplicity), considering that some processes may output no value. In a distributed system with n processes, of which up to t ≤ n can crash, we provide a complete characterization of the tight conditions on n and t under which every class of tasks with binary outputs is solvable, for both synchronous and asynchronous systems. This output-set approach yields highly general results: it unifies multiple distributed computing problems, such as binary consensus and symmetry breaking, and it produces impossibility proofs that hold for stronger task formulations, including those that consider validity, account for value multiplicity, or move beyond binary outputs.
Cite as

Timothé Albouy, Antonio Fernández Anta, Chryssis Georgiou, Nicolas Nicolaou, and Junlang Wang. Tight Conditions for Binary-Output Tasks Under Crashes. In 29th International Conference on Principles of Distributed Systems (OPODIS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 361, pp. 5:1-5:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

Copy BibTex To Clipboard

@InProceedings{albouy_et_al:LIPIcs.OPODIS.2025.5,
  author =	{Albouy, Timoth\'{e} and Fern\'{a}ndez Anta, Antonio and Georgiou, Chryssis and Nicolaou, Nicolas and Wang, Junlang},
  title =	{{Tight Conditions for Binary-Output Tasks Under Crashes}},
  booktitle =	{29th International Conference on Principles of Distributed Systems (OPODIS 2025)},
  pages =	{5:1--5:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-409-3},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{361},
  editor =	{Arusoaie, Andrei and Onica, Emanuel and Spear, Michael and Tucci-Piergiovanni, Sara},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2025.5},
  URN =		{urn:nbn:de:0030-drops-251786},
  doi =		{10.4230/LIPIcs.OPODIS.2025.5},
  annote =	{Keywords: Distributed solvability, Asynchrony, Synchrony, Impossibility proofs, Binary-output tasks, Crash tolerance, Disagreement}
}
Document
DOI: 10.4230/LIPIcs.DISC.2025.15
Asynchronous Latency and Fast Atomic Snapshot

Authors: João Paulo Bezerra, Luciano Freitas, Petr Kuznetsov, and Matthieu Rambaud

Published in: LIPIcs, Volume 356, 39th International Symposium on Distributed Computing (DISC 2025)

Abstract
This paper introduces a novel, fast atomic-snapshot protocol for asynchronous message-passing systems. In the process of defining what "fast" means exactly, we spot a few interesting issues that arise when conventional time metrics are applied to long-lived asynchronous algorithms. We reveal some gaps in latency claims made in earlier work on snapshot algorithms, which hamper their comparative time-complexity analysis. We then come up with a new unifying time-complexity metric that captures the latency of an operation in an asynchronous, long-lived implementation. This allows us to formally grasp latency improvements of our atomic-snapshot algorithm with respect to the state-of-the-art protocols: optimal latency in fault-free runs without contention, short constant latency in fault-free runs with contention, the worst-case latency proportional to the number of active concurrent failures, and constant amortized latency.
Cite as

João Paulo Bezerra, Luciano Freitas, Petr Kuznetsov, and Matthieu Rambaud. Asynchronous Latency and Fast Atomic Snapshot. In 39th International Symposium on Distributed Computing (DISC 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 356, pp. 15:1-15:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

Copy BibTex To Clipboard

@InProceedings{bezerra_et_al:LIPIcs.DISC.2025.15,
  author =	{Bezerra, Jo\~{a}o Paulo and Freitas, Luciano and Kuznetsov, Petr and Rambaud, Matthieu},
  title =	{{Asynchronous Latency and Fast Atomic Snapshot}},
  booktitle =	{39th International Symposium on Distributed Computing (DISC 2025)},
  pages =	{15:1--15:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-402-4},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{356},
  editor =	{Kowalski, Dariusz R.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2025.15},
  URN =		{urn:nbn:de:0030-drops-248326},
  doi =		{10.4230/LIPIcs.DISC.2025.15},
  annote =	{Keywords: Asynchronous systems, time complexity, atomic snapshot, crash faults}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2024.21
No Symmetric Broadcast Abstraction Characterizes k-Set-Agreement in Message-Passing Systems

Authors: Sylvain Gay, Achour Mostéfaoui, and Matthieu Perrin

Published in: LIPIcs, Volume 324, 28th International Conference on Principles of Distributed Systems (OPODIS 2024)

Abstract
This paper explores the relationship between broadcast abstractions and the k-set agreement (k-SA) problem in crash-prone asynchronous distributed systems. It specifically investigates whether any broadcast abstraction is computationally equivalent to k-SA in message-passing systems. A key contribution of the paper is the delineation of the realm of "meaningful" broadcast abstractions, through the introduction of two new symmetry properties: compositionality and content-neutrality, inspired by the principle of network neutrality. Such preciseness in definition is essential for this paper’s scope, as our aim is not to characterize the computing power of a specific broadcast abstraction, but rather to explore the domain of broadcast abstractions as a whole, in search of a broadcast abstraction with certain characteristics. The paper’s main contribution is the proof that no broadcast abstraction, which is both content-neutral and compositional, is computationally equivalent to k-set agreement when 1 < k < n, in the crash-prone asynchronous message-passing model. To the best of our knowledge, this result represents the first instance of showing that a coordination problem cannot be expressed by an equivalent broadcast abstraction. It does not establish the absence of an implementation, but rather the absence of a specification that possesses certain properties.
Cite as

Sylvain Gay, Achour Mostéfaoui, and Matthieu Perrin. No Symmetric Broadcast Abstraction Characterizes k-Set-Agreement in Message-Passing Systems. In 28th International Conference on Principles of Distributed Systems (OPODIS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 324, pp. 21:1-21:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

Copy BibTex To Clipboard

@InProceedings{gay_et_al:LIPIcs.OPODIS.2024.21,
  author =	{Gay, Sylvain and Most\'{e}faoui, Achour and Perrin, Matthieu},
  title =	{{No Symmetric Broadcast Abstraction Characterizes k-Set-Agreement in Message-Passing Systems}},
  booktitle =	{28th International Conference on Principles of Distributed Systems (OPODIS 2024)},
  pages =	{21:1--21:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-360-7},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{324},
  editor =	{Bonomi, Silvia and Galletta, Letterio and Rivi\`{e}re, Etienne and Schiavoni, Valerio},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2024.21},
  URN =		{urn:nbn:de:0030-drops-225573},
  doi =		{10.4230/LIPIcs.OPODIS.2024.21},
  annote =	{Keywords: Agreement problem, Asynchronous system, Broadcast abstraction, Communication abstraction, Compositionality, Message-passing system, Network neutrality, Process crash, k-Set agreement, Wait-free model, Total order broadcast}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2020.16
Optimal Resilience in Systems That Mix Shared Memory and Message Passing

Authors: Hagit Attiya, Sweta Kumari, and Noa Schiller

Published in: LIPIcs, Volume 184, 24th International Conference on Principles of Distributed Systems (OPODIS 2020)

Abstract
We investigate the minimal number of failures that can partition a system where processes communicate both through shared memory and by message passing. We prove that this number precisely captures the resilience that can be achieved by algorithms that implement a variety of shared objects, like registers and atomic snapshots, and solve common tasks, like randomized consensus, approximate agreement and renaming. This has implications for the m&m-model of [Aguilera et al., 2018] and for the hybrid, cluster-based model of [Damien Imbs and Michel Raynal, 2013; Michel Raynal and Jiannong Cao, 2019].
Cite as

Hagit Attiya, Sweta Kumari, and Noa Schiller. Optimal Resilience in Systems That Mix Shared Memory and Message Passing. In 24th International Conference on Principles of Distributed Systems (OPODIS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 184, pp. 16:1-16:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

Copy BibTex To Clipboard

@InProceedings{attiya_et_al:LIPIcs.OPODIS.2020.16,
  author =	{Attiya, Hagit and Kumari, Sweta and Schiller, Noa},
  title =	{{Optimal Resilience in Systems That Mix Shared Memory and Message Passing}},
  booktitle =	{24th International Conference on Principles of Distributed Systems (OPODIS 2020)},
  pages =	{16:1--16:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-176-4},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{184},
  editor =	{Bramas, Quentin and Oshman, Rotem and Romano, Paolo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2020.16},
  URN =		{urn:nbn:de:0030-drops-135019},
  doi =		{10.4230/LIPIcs.OPODIS.2020.16},
  annote =	{Keywords: fault resilience, m\&m model, cluster-based model, randomized consensus, approximate agreement, renaming, register implementations, atomic snapshots}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2017.9
Progress-Space Tradeoffs in Single-Writer Memory Implementations

Authors: Damien Imbs, Petr Kuznetsov, and Thibault Rieutord

Published in: LIPIcs, Volume 95, 21st International Conference on Principles of Distributed Systems (OPODIS 2017)

Abstract
Many algorithms designed for shared-memory distributed systems assume the single-writer multi- reader (SWMR) setting where each process is provided with a unique register that can only be written by the process and read by all. In a system where computation is performed by a bounded number n of processes coming from a large (possibly unbounded) set of potential participants, the assumption of an SWMR memory is no longer reasonable. If only a bounded number of multi- writer multi-reader (MWMR) registers are provided, we cannot rely on an a priori assignment of processes to registers. In this setting, implementing an SWMR memory, or equivalently, ensuring stable writes (i.e., every written value persists in the memory), is desirable. In this paper, we propose an SWMR implementation that adapts the number of MWMR registers used to the desired progress condition. For any given k from 1 to n, we present an algorithm that uses n + k − 1 registers to implement a k-lock-free SWMR memory. In the special case of 2-lock-freedom, we also give a matching lower bound of n + 1 registers, which supports our conjecture that the algorithm is space-optimal. Our lower bound holds for the strictly weaker progress condition of 2-obstruction-freedom, which suggests that the space complexity for k-obstruction-free and k-lock-free SWMR implementations might coincide.
Cite as

Damien Imbs, Petr Kuznetsov, and Thibault Rieutord. Progress-Space Tradeoffs in Single-Writer Memory Implementations. In 21st International Conference on Principles of Distributed Systems (OPODIS 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 95, pp. 9:1-9:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

Copy BibTex To Clipboard

@InProceedings{imbs_et_al:LIPIcs.OPODIS.2017.9,
  author =	{Imbs, Damien and Kuznetsov, Petr and Rieutord, Thibault},
  title =	{{Progress-Space Tradeoffs in Single-Writer Memory Implementations}},
  booktitle =	{21st International Conference on Principles of Distributed Systems (OPODIS 2017)},
  pages =	{9:1--9:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-061-3},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{95},
  editor =	{Aspnes, James and Bessani, Alysson and Felber, Pascal and Leit\~{a}o, Jo\~{a}o},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2017.9},
  URN =		{urn:nbn:de:0030-drops-86290},
  doi =		{10.4230/LIPIcs.OPODIS.2017.9},
  annote =	{Keywords: Single-writer memory implementation, comparison-based algorithms, space complexity, progress conditions}
}
Document
DOI: 10.4230/LIPIcs.DISC.2017.27
Which Broadcast Abstraction Captures k-Set Agreement?

Authors: Damien Imbs, Achour Mostéfaoui, Matthieu Perrin, and Michel Raynal

Published in: LIPIcs, Volume 91, 31st International Symposium on Distributed Computing (DISC 2017)

Abstract
It is well-known that consensus (one-set agreement) and total order broadcast are equivalent in asynchronous systems prone to process crash failures. Considering wait-free systems, this article addresses and answers the following question: which is the communication abstraction that "captures" k-set agreement? To this end, it introduces a new broadcast communication abstraction, called k-BO-Broadcast, which restricts the disagreement on the local deliveries of the messages that have been broadcast (1-BO-Broadcast boils down to total order broadcast). Hence, in this context, k=1 is not a special number, but only the first integer in an increasing integer sequence. This establishes a new "correspondence" between distributed agreement problems and communication abstractions, which enriches our understanding of the relations linking fundamental issues of fault-tolerant distributed computing.
Cite as

Damien Imbs, Achour Mostéfaoui, Matthieu Perrin, and Michel Raynal. Which Broadcast Abstraction Captures k-Set Agreement?. In 31st International Symposium on Distributed Computing (DISC 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 91, pp. 27:1-27:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

Copy BibTex To Clipboard

@InProceedings{imbs_et_al:LIPIcs.DISC.2017.27,
  author =	{Imbs, Damien and Most\'{e}faoui, Achour and Perrin, Matthieu and Raynal, Michel},
  title =	{{Which Broadcast Abstraction Captures k-Set Agreement?}},
  booktitle =	{31st International Symposium on Distributed Computing (DISC 2017)},
  pages =	{27:1--27:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-053-8},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{91},
  editor =	{Richa, Andr\'{e}a},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2017.27},
  URN =		{urn:nbn:de:0030-drops-79943},
  doi =		{10.4230/LIPIcs.DISC.2017.27},
  annote =	{Keywords: Agreement problem, Antichain, Asynchronous system, Communication abstraction, Consensus, Message-passing system, Partially ordered set, Process crash}
}
Document
DOI: 10.4230/DagRep.6.7.31
Topological Methods in Distributed Computing (Dagstuhl Seminar 16282)

Authors: Dmitry Feichtner-Kozlov and Damien Imbs

Published in: Dagstuhl Reports, Volume 6, Issue 7 (2016)

Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 16282 "Topological Methods in Distributed Computing", which was attended by 22 international researchers, both junior and senior. In the last 10--15 years, there has been an increasing body of work on applications of topology in theoretical distributed computing. This seminar brought together computer scientists working in theoretical distributed computing and mathematicians working in combinatorial topology, leading to interesting new collaborations. This report gathers abstracts of the talks given by the participants and of the group research sessions that happened during the seminar.
Cite as

Dmitry Feichtner-Kozlov and Damien Imbs. Topological Methods in Distributed Computing (Dagstuhl Seminar 16282). In Dagstuhl Reports, Volume 6, Issue 7, pp. 31-41, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)

Copy BibTex To Clipboard

@Article{feichtnerkozlov_et_al:DagRep.6.7.31,
  author =	{Feichtner-Kozlov, Dmitry and Imbs, Damien},
  title =	{{Topological Methods in Distributed Computing (Dagstuhl Seminar 16282)}},
  pages =	{31--41},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2016},
  volume =	{6},
  number =	{7},
  editor =	{Feichtner-Kozlov, Dmitry and Imbs, Damien},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.6.7.31},
  URN =		{urn:nbn:de:0030-drops-67614},
  doi =		{10.4230/DagRep.6.7.31},
  annote =	{Keywords: combinatorial topology, concurrency, distributed protocols, shared-memory communication, solvability}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2015.26
The Synchronization Power of Atomic Bitwise Operations

Authors: Damien Imbs

Published in: LIPIcs, Volume 46, 19th International Conference on Principles of Distributed Systems (OPODIS 2015)

Abstract
In a distributed system, processes must reach a certain level of synchronization to solve a common problem. The strongest form of synchronization can be reached through consensus: all the processes must agree on a common value that has been proposed by one of them. Consensus is universal in shared memory systems: any type of shared object can be implemented using it. Unfortunately, consensus is impossible to solve using only shared registers when processes can crash. To circumvent this impossibility, one can use stronger objects, for example Test&Set or Compare&Swap. The synchronization power of these objects can be measured using the concept of Consensus Number: the maximum number of processes for which they can solve consensus in a crash-prone system. Bitwise AND, OR and XOR operations are very widely used, but have received little attention in the distributed setting. Because bitwise operations are available in most modern processors, they can constitute a valuable tool for synchronization in distributed systems. It is then natural to consider the level of synchronization that these operations can achieve. This paper introduces shared AND/OR and AND/OR/XOR registers. A shared AND/OR register consists of an array of x bits and offers three atomic operations: AND and OR operations, which take an array of x bits as parameter and change the state of the register by applying the corresponding bitwise operation, and a read operation which returns the content of the array. A shared AND/OR/XOR register additionally offers a XOR operation. We show that shared AND/OR registers of x bits have consensus number lfloor (x+1)/2 rfloor, by presenting an algorithm that solves consensus using these registers, and by proving that consensus cannot be solved for n processes using AND/OR registers that have strictly less than 2n-1 bits. We then show that shared AND/OR/XOR registers of x bits have consensus number x using a similar technique.
Cite as

Damien Imbs. The Synchronization Power of Atomic Bitwise Operations. In 19th International Conference on Principles of Distributed Systems (OPODIS 2015). Leibniz International Proceedings in Informatics (LIPIcs), Volume 46, pp. 26:1-26:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)

Copy BibTex To Clipboard

@InProceedings{imbs:LIPIcs.OPODIS.2015.26,
  author =	{Imbs, Damien},
  title =	{{The Synchronization Power of Atomic Bitwise Operations}},
  booktitle =	{19th International Conference on Principles of Distributed Systems (OPODIS 2015)},
  pages =	{26:1--26:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-98-9},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{46},
  editor =	{Anceaume, Emmanuelle and Cachin, Christian and Potop-Butucaru, Maria},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2015.26},
  URN =		{urn:nbn:de:0030-drops-66151},
  doi =		{10.4230/LIPIcs.OPODIS.2015.26},
  annote =	{Keywords: Asynchronous systems, Binary operations, Consensus, Consensus number, Read/write shared memory, Shared objects, Synchronization, Wait-freedom}
}
  • Refine by Type
  • 8 Document/PDF
  • 3 Document/HTML

  • Refine by Publication Year
  • 1 2026
  • 2 2025
  • 1 2021
  • 1 2018
  • 1 2017
  • Show More...

  • Refine by Author
  • 4 Imbs, Damien
  • 2 Kuznetsov, Petr
  • 2 Mostéfaoui, Achour
  • 2 Perrin, Matthieu
  • 1 Albouy, Timothé
  • Show More...

  • Refine by Series/Journal
  • 7 LIPIcs
  • 1 DagRep

  • Refine by Classification
  • 2 Theory of computation → Distributed algorithms
  • 2 Theory of computation → Distributed computing models
  • 1 Computer systems organization → Dependable and fault-tolerant systems and networks
  • 1 Computing methodologies → Distributed algorithms
  • 1 Networks → Network properties
  • Show More...

  • Refine by Keyword
  • 2 Agreement problem
  • 2 Asynchronous system
  • 2 Asynchronous systems
  • 2 Communication abstraction
  • 2 Consensus
  • Show More...

Any Issues?
X

Feedback on the Current Page

CAPTCHA

Thanks for your feedback!

Feedback submitted to Dagstuhl Publishing

Could not send message

Please try again later or send an E-mail
© 2023-2026 Schloss Dagstuhl – LZI GmbH Schloss Dagstuhl – LZI GmbH About DROPS Imprint Privacy Contact