104 Search Results for "Oshman, Rotem"


Volume

LIPIcs, Volume 281

37th International Symposium on Distributed Computing (DISC 2023)

DISC 2023, October 10-12, 2023, L'Aquila, Italy

Editors: Rotem Oshman

Volume

LIPIcs, Volume 184

24th International Conference on Principles of Distributed Systems (OPODIS 2020)

OPODIS 2020, December 14-16, 2020, Strasbourg, France (Virtual Conference)

Editors: Quentin Bramas, Rotem Oshman, and Paolo Romano

Document
On Polynomial Time Local Decision

Authors: Eden Aldema Tshuva and Rotem Oshman

Published in: LIPIcs, Volume 286, 27th International Conference on Principles of Distributed Systems (OPODIS 2023)


Abstract
The field of distributed local decision studies the power of local network algorithms, where each network can see only its own local neighborhood, and must act based on this restricted information. Traditionally, the nodes of the network are assumed to have unbounded local computation power, and this makes the model incomparable with centralized notions of efficiency, namely, the classes 𝖯 and NP. In this work we seek to bridge this gap by studying local algorithms where the nodes are required to be computationally efficient: we introduce the classes PLD and NPLD of polynomial-time local decision and non-deterministic polynomial-time local decision, respectively, and compare them to the centralized complexity classes 𝖯 and NP, and to the distributed classes LD and NLD, which correspond to local deterministic and non-deterministic decision, respectively. We show that for deterministic algorithms, requiring both computational and distributed efficiency is likely to be more restrictive than either requirement alone: if the nodes do not know the network size, then PLD ⊊ LD ∩ 𝖯 holds unconditionally; if the network size is known to all nodes, then the same separation holds under a widely believed complexity assumption (UP ∩ coUP ≠ 𝖯). However, when nondeterminism is introduced, this distinction vanishes, and NPLD = NLD ∩ NP. To complete the picture, we extend the classes PLD and NPLD into a hierarchy akin to the centralized polynomial hierarchy, and we characterize its connections to the centralized polynomial hierarchy and to the distributed local decision hierarchy of Balliu, D'Angelo, Fraigniaud, and Olivetti.

Cite as

Eden Aldema Tshuva and Rotem Oshman. On Polynomial Time Local Decision. In 27th International Conference on Principles of Distributed Systems (OPODIS 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 286, pp. 27:1-27:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{aldematshuva_et_al:LIPIcs.OPODIS.2023.27,
  author =	{Aldema Tshuva, Eden and Oshman, Rotem},
  title =	{{On Polynomial Time Local Decision}},
  booktitle =	{27th International Conference on Principles of Distributed Systems (OPODIS 2023)},
  pages =	{27:1--27:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-308-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{286},
  editor =	{Bessani, Alysson and D\'{e}fago, Xavier and Nakamura, Junya and Wada, Koichi and Yamauchi, Yukiko},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2023.27},
  URN =		{urn:nbn:de:0030-drops-195179},
  doi =		{10.4230/LIPIcs.OPODIS.2023.27},
  annote =	{Keywords: Local Decision, Polynomial-Time, LD, NLD}
}
Document
Complete Volume
LIPIcs, Volume 281, DISC 2023, Complete Volume

Authors: Rotem Oshman

Published in: LIPIcs, Volume 281, 37th International Symposium on Distributed Computing (DISC 2023)


Abstract
LIPIcs, Volume 281, DISC 2023, Complete Volume

Cite as

37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 1-836, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@Proceedings{oshman:LIPIcs.DISC.2023,
  title =	{{LIPIcs, Volume 281, DISC 2023, Complete Volume}},
  booktitle =	{37th International Symposium on Distributed Computing (DISC 2023)},
  pages =	{1--836},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-301-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{281},
  editor =	{Oshman, Rotem},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2023},
  URN =		{urn:nbn:de:0030-drops-191258},
  doi =		{10.4230/LIPIcs.DISC.2023},
  annote =	{Keywords: LIPIcs, Volume 281, DISC 2023, Complete Volume}
}
Document
Front Matter
Front Matter, Table of Contents, Preface, Conference Organization

Authors: Rotem Oshman

Published in: LIPIcs, Volume 281, 37th International Symposium on Distributed Computing (DISC 2023)


Abstract
Front Matter, Table of Contents, Preface, Conference Organization

Cite as

37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 0:i-0:xx, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{oshman:LIPIcs.DISC.2023.0,
  author =	{Oshman, Rotem},
  title =	{{Front Matter, Table of Contents, Preface, Conference Organization}},
  booktitle =	{37th International Symposium on Distributed Computing (DISC 2023)},
  pages =	{0:i--0:xx},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-301-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{281},
  editor =	{Oshman, Rotem},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2023.0},
  URN =		{urn:nbn:de:0030-drops-191265},
  doi =		{10.4230/LIPIcs.DISC.2023.0},
  annote =	{Keywords: Front Matter, Table of Contents, Preface, Conference Organization}
}
Document
Colordag: An Incentive-Compatible Blockchain

Authors: Ittai Abraham, Danny Dolev, Ittay Eyal, and Joseph Y. Halpern

Published in: LIPIcs, Volume 281, 37th International Symposium on Distributed Computing (DISC 2023)


Abstract
We present Colordag, a blockchain protocol where following the prescribed strategy is, with high probability, a best response as long as all miners have less than 1/2 of the mining power. We prove the correctness of Colordag even if there is an extremely powerful adversary who knows future actions of the scheduler: specifically, when agents will generate blocks and when messages will arrive. The state-of-the-art protocol, Fruitchain, is an ε-Nash equilibrium as long as all miners have less than 1/2 of the mining power. However, there is a simple deviation that guarantees that deviators are never worse off than they would be by following Fruitchain, and can sometimes do better. Thus, agents are motivated to deviate. Colordag implements a solution concept that we call ε-sure Nash equilibrium and does not suffer from this problem. Because it is an ε-sure Nash equilibrium, Colordag is an ε-Nash equilibrium and with probability 1-ε is a best response.

Cite as

Ittai Abraham, Danny Dolev, Ittay Eyal, and Joseph Y. Halpern. Colordag: An Incentive-Compatible Blockchain. In 37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 1:1-1:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{abraham_et_al:LIPIcs.DISC.2023.1,
  author =	{Abraham, Ittai and Dolev, Danny and Eyal, Ittay and Halpern, Joseph Y.},
  title =	{{Colordag: An Incentive-Compatible Blockchain}},
  booktitle =	{37th International Symposium on Distributed Computing (DISC 2023)},
  pages =	{1:1--1:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-301-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{281},
  editor =	{Oshman, Rotem},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2023.1},
  URN =		{urn:nbn:de:0030-drops-191272},
  doi =		{10.4230/LIPIcs.DISC.2023.1},
  annote =	{Keywords: Game theory, incentives, blockchain}
}
Document
Certified Round Complexity of Self-Stabilizing Algorithms

Authors: Karine Altisen, Pierre Corbineau, and Stéphane Devismes

Published in: LIPIcs, Volume 281, 37th International Symposium on Distributed Computing (DISC 2023)


Abstract
A proof assistant is an appropriate tool to write sound proofs. The need of such tools in distributed computing grows over the years due to the scientific progress that leads algorithmic designers to consider always more difficult problems. In that spirit, the PADEC Coq library has been developed to certify self-stabilizing algorithms. Efficiency of self-stabilizing algorithms is mainly evaluated by comparing their stabilization times in rounds, the time unit that is primarily used in the self-stabilizing area. In this paper, we introduce the notion of rounds in the PADEC library together with several formal tools to help the certification of the complexity analysis of self-stabilizing algorithms. We validate our approach by certifying the stabilization time in rounds of the classical Dolev et al’s self-stabilizing Breadth-first Search spanning tree construction.

Cite as

Karine Altisen, Pierre Corbineau, and Stéphane Devismes. Certified Round Complexity of Self-Stabilizing Algorithms. In 37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 2:1-2:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{altisen_et_al:LIPIcs.DISC.2023.2,
  author =	{Altisen, Karine and Corbineau, Pierre and Devismes, St\'{e}phane},
  title =	{{Certified Round Complexity of Self-Stabilizing Algorithms}},
  booktitle =	{37th International Symposium on Distributed Computing (DISC 2023)},
  pages =	{2:1--2:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-301-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{281},
  editor =	{Oshman, Rotem},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2023.2},
  URN =		{urn:nbn:de:0030-drops-191284},
  doi =		{10.4230/LIPIcs.DISC.2023.2},
  annote =	{Keywords: Certification, proof assistant, Coq, self-stabilization, round complexity}
}
Document
Network Agnostic Perfectly Secure MPC Against General Adversaries

Authors: Ananya Appan, Anirudh Chandramouli, and Ashish Choudhury

Published in: LIPIcs, Volume 281, 37th International Symposium on Distributed Computing (DISC 2023)


Abstract
In this work, we study perfectly-secure multi-party computation (MPC) against general (non-threshold) adversaries. Known protocols are secure against 𝒬^{(3)} and 𝒬^{(4)} adversary structures in a synchronous and an asynchronous network respectively. We address the existence of a single protocol which remains secure against 𝒬^{(3)} and 𝒬^{(4)} adversary structures in a synchronous and in an asynchronous network respectively, where the parties are unaware of the network type. We design the first such protocol against general adversaries. Our result generalizes the result of Appan, Chandramouli and Choudhury (PODC 2022), which presents such a protocol against threshold adversaries.

Cite as

Ananya Appan, Anirudh Chandramouli, and Ashish Choudhury. Network Agnostic Perfectly Secure MPC Against General Adversaries. In 37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 3:1-3:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{appan_et_al:LIPIcs.DISC.2023.3,
  author =	{Appan, Ananya and Chandramouli, Anirudh and Choudhury, Ashish},
  title =	{{Network Agnostic Perfectly Secure MPC Against General Adversaries}},
  booktitle =	{37th International Symposium on Distributed Computing (DISC 2023)},
  pages =	{3:1--3:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-301-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{281},
  editor =	{Oshman, Rotem},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2023.3},
  URN =		{urn:nbn:de:0030-drops-191294},
  doi =		{10.4230/LIPIcs.DISC.2023.3},
  annote =	{Keywords: Verifiable Secret Sharing, Byzantine Agreement, Perfect Security}
}
Document
One Step Forward, One Step Back: FLP-Style Proofs and the Round-Reduction Technique for Colorless Tasks

Authors: Hagit Attiya, Pierre Fraigniaud, Ami Paz, and Sergio Rajsbaum

Published in: LIPIcs, Volume 281, 37th International Symposium on Distributed Computing (DISC 2023)


Abstract
The paper compares two generic techniques for deriving lower bounds and impossibility results in distributed computing. First, we prove a speedup theorem (a-la Brandt, 2019), for wait-free colorless algorithms, aiming at capturing the essence of the seminal round-reduction proof establishing a lower bound on the number of rounds for 3-coloring a cycle (Linial, 1992), and going by backward induction. Second, we consider FLP-style proofs, aiming at capturing the essence of the seminal consensus impossibility proof (Fischer, Lynch, and Paterson, 1985) and using forward induction. We show that despite their very different natures, these two forms of proof are tightly connected. In particular, we show that for every colorless task Π, if there is a round-reduction proof establishing the impossibility of solving Π using wait-free colorless algorithms, then there is an FLP-style proof establishing the same impossibility. For 1-dimensional colorless tasks (for an arbitrarily number n ≥ 2 of processes), we prove that the two proof techniques have exactly the same power, and more importantly, both are complete: if a 1-dimensional colorless task is not wait-free solvable by n ≥ 2 processes, then the impossibility can be proved by both proof techniques. Moreover, a round-reduction proof can be automatically derived, and an FLP-style proof can be automatically generated from it. Finally, we illustrate the use of these two techniques by establishing the impossibility of solving any colorless covering task of arbitrary dimension by wait-free algorithms.

Cite as

Hagit Attiya, Pierre Fraigniaud, Ami Paz, and Sergio Rajsbaum. One Step Forward, One Step Back: FLP-Style Proofs and the Round-Reduction Technique for Colorless Tasks. In 37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 4:1-4:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{attiya_et_al:LIPIcs.DISC.2023.4,
  author =	{Attiya, Hagit and Fraigniaud, Pierre and Paz, Ami and Rajsbaum, Sergio},
  title =	{{One Step Forward, One Step Back: FLP-Style Proofs and the Round-Reduction Technique for Colorless Tasks}},
  booktitle =	{37th International Symposium on Distributed Computing (DISC 2023)},
  pages =	{4:1--4:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-301-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{281},
  editor =	{Oshman, Rotem},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2023.4},
  URN =		{urn:nbn:de:0030-drops-191304},
  doi =		{10.4230/LIPIcs.DISC.2023.4},
  annote =	{Keywords: Wait-free computing, lower bounds}
}
Document
Topological Characterization of Task Solvability in General Models of Computation

Authors: Hagit Attiya, Armando Castañeda, and Thomas Nowak

Published in: LIPIcs, Volume 281, 37th International Symposium on Distributed Computing (DISC 2023)


Abstract
The famous asynchronous computability theorem (ACT) relates the existence of an asynchronous wait-free shared memory protocol for solving a task with the existence of a simplicial map from a subdivision of the simplicial complex representing the inputs to the simplicial complex representing the allowable outputs. The original theorem relies on a correspondence between protocols and simplicial maps in round-structured models of computation that induce a compact topology. This correspondence, however, is far from obvious for computation models that induce a non-compact topology, and indeed previous attempts to extend the ACT have failed. This paper shows that in every non-compact model, protocols solving tasks correspond to simplicial maps that need to be continuous. It first proves a generalized ACT for sub-IIS models, some of which are non-compact, and applies it to the set agreement task. Then it proves that in general models too, protocols are simplicial maps that need to be continuous, hence showing that the topological approach is universal. Finally, it shows that the approach used in ACT that equates protocols and simplicial complexes actually works for every compact model. Our study combines, for the first time, combinatorial and point-set topological aspects of the executions admitted by the computation model.

Cite as

Hagit Attiya, Armando Castañeda, and Thomas Nowak. Topological Characterization of Task Solvability in General Models of Computation. In 37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 5:1-5:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{attiya_et_al:LIPIcs.DISC.2023.5,
  author =	{Attiya, Hagit and Casta\~{n}eda, Armando and Nowak, Thomas},
  title =	{{Topological Characterization of Task Solvability in General Models of Computation}},
  booktitle =	{37th International Symposium on Distributed Computing (DISC 2023)},
  pages =	{5:1--5:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-301-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{281},
  editor =	{Oshman, Rotem},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2023.5},
  URN =		{urn:nbn:de:0030-drops-191315},
  doi =		{10.4230/LIPIcs.DISC.2023.5},
  annote =	{Keywords: task solvability, combinatorial topology, point-set topology}
}
Document
Base Fee Manipulation in Ethereum’s EIP-1559 Transaction Fee Mechanism

Authors: Sarah Azouvi, Guy Goren, Lioba Heimbach, and Alexander Hicks

Published in: LIPIcs, Volume 281, 37th International Symposium on Distributed Computing (DISC 2023)


Abstract
In 2021 Ethereum adjusted the transaction pricing mechanism by implementing EIP-1559, which introduces the base fee - a network fee that is burned and dynamically adjusts to the network demand. The authors of the Ethereum Improvement Proposal (EIP) noted that a miner with more than 50% of the mining power could be incentivized to deviate from the honest mining strategy. Instead, such a miner could propose a series of empty blocks to artificially lower demand and increase her future rewards. In this paper, we generalize this attack and show that under rational player behavior, deviating from the honest strategy can be profitable for a miner with less than 50% of the mining power. We show that even when miners do not collaborate, it is at times rational for smaller miners to join the attack. Finally, we propose a mitigation to address the identified vulnerability.

Cite as

Sarah Azouvi, Guy Goren, Lioba Heimbach, and Alexander Hicks. Base Fee Manipulation in Ethereum’s EIP-1559 Transaction Fee Mechanism. In 37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 6:1-6:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{azouvi_et_al:LIPIcs.DISC.2023.6,
  author =	{Azouvi, Sarah and Goren, Guy and Heimbach, Lioba and Hicks, Alexander},
  title =	{{Base Fee Manipulation in Ethereum’s EIP-1559 Transaction Fee Mechanism}},
  booktitle =	{37th International Symposium on Distributed Computing (DISC 2023)},
  pages =	{6:1--6:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-301-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{281},
  editor =	{Oshman, Rotem},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2023.6},
  URN =		{urn:nbn:de:0030-drops-191325},
  doi =		{10.4230/LIPIcs.DISC.2023.6},
  annote =	{Keywords: blockchain, Ethereum, transaction fee mechanism, EIP-1559}
}
Document
On the Node-Averaged Complexity of Locally Checkable Problems on Trees

Authors: Alkida Balliu, Sebastian Brandt, Fabian Kuhn, Dennis Olivetti, and Gustav Schmid

Published in: LIPIcs, Volume 281, 37th International Symposium on Distributed Computing (DISC 2023)


Abstract
Over the past decade, a long line of research has investigated the distributed complexity landscape of locally checkable labeling (LCL) problems on bounded-degree graphs, culminating in an almost-complete classification on general graphs and a complete classification on trees. The latter states that, on bounded-degree trees, any LCL problem has deterministic worst-case time complexity O(1), Θ(log^* n), Θ(log n), or Θ(n^{1/k}) for some positive integer k, and all of those complexity classes are nonempty. Moreover, randomness helps only for (some) problems with deterministic worst-case complexity Θ(log n), and if randomness helps (asymptotically), then it helps exponentially. In this work, we study how many distributed rounds are needed on average per node in order to solve an LCL problem on trees. We obtain a partial classification of the deterministic node-averaged complexity landscape for LCL problems. As our main result, we show that every problem with worst-case round complexity O(log n) has deterministic node-averaged complexity O(log^* n). We further establish bounds on the node-averaged complexity of problems with worst-case complexity Θ(n^{1/k}): we show that all these problems have node-averaged complexity Ω̃(n^{1 / (2^k - 1)}), and that this lower bound is tight for some problems.

Cite as

Alkida Balliu, Sebastian Brandt, Fabian Kuhn, Dennis Olivetti, and Gustav Schmid. On the Node-Averaged Complexity of Locally Checkable Problems on Trees. In 37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 7:1-7:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{balliu_et_al:LIPIcs.DISC.2023.7,
  author =	{Balliu, Alkida and Brandt, Sebastian and Kuhn, Fabian and Olivetti, Dennis and Schmid, Gustav},
  title =	{{On the Node-Averaged Complexity of Locally Checkable Problems on Trees}},
  booktitle =	{37th International Symposium on Distributed Computing (DISC 2023)},
  pages =	{7:1--7:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-301-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{281},
  editor =	{Oshman, Rotem},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2023.7},
  URN =		{urn:nbn:de:0030-drops-191330},
  doi =		{10.4230/LIPIcs.DISC.2023.7},
  annote =	{Keywords: distributed graph algorithms, locally checkable labelings, node-averaged complexity, trees}
}
Document
Treasure Hunt with Volatile Pheromones

Authors: Evangelos Bampas, Joffroy Beauquier, Janna Burman, and William Guy--Obé

Published in: LIPIcs, Volume 281, 37th International Symposium on Distributed Computing (DISC 2023)


Abstract
In the treasure hunt problem, a team of mobile agents need to locate a single treasure that is hidden in their environment. We consider the problem in the discrete setting of an oriented infinite rectangular grid, where agents are modeled as synchronous identical deterministic time-limited finite-state automata, originating at a rate of one agent per round from the origin. Agents perish τ rounds after their creation, where τ ≥ 1 is a parameter of the model. An algorithm solves the treasure hunt problem if every grid position at distance τ or less from the origin is visited by at least one agent. Agents may communicate only by leaving indistinguishable traces (pheromone) on the nodes of the grid, which can be sensed by agents in adjacent nodes and thus modify their behavior. The novelty of our approach is that, in contrast to existing literature that uses permanent pheromone markers, we assume that pheromone traces evaporate over μ rounds from the moment they were placed on a node, where μ ≥ 1 is another parameter of the model. We look for uniform algorithms that solve the problem without knowledge of the parameter values, and we investigate the implications of this very weak communication mechanism to the treasure hunt problem. We show that, if pheromone persists for at least two rounds (μ ≥ 2), then there exists a treasure hunt algorithm for all values of agent lifetime. We also develop a more sophisticated algorithm that works for all values of μ, hence also for the fastest possible pheromone evaporation of μ = 1, but only if agent lifetime is at least 16.

Cite as

Evangelos Bampas, Joffroy Beauquier, Janna Burman, and William Guy--Obé. Treasure Hunt with Volatile Pheromones. In 37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 8:1-8:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{bampas_et_al:LIPIcs.DISC.2023.8,
  author =	{Bampas, Evangelos and Beauquier, Joffroy and Burman, Janna and Guy--Ob\'{e}, William},
  title =	{{Treasure Hunt with Volatile Pheromones}},
  booktitle =	{37th International Symposium on Distributed Computing (DISC 2023)},
  pages =	{8:1--8:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-301-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{281},
  editor =	{Oshman, Rotem},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2023.8},
  URN =		{urn:nbn:de:0030-drops-191343},
  doi =		{10.4230/LIPIcs.DISC.2023.8},
  annote =	{Keywords: Mobile Agents, Exploration, Search, Treasure Hunt, Pheromone, Evaporation}
}
Document
The FIDS Theorems: Tensions Between Multinode and Multicore Performance in Transactional Systems

Authors: Naama Ben-David, Gal Sela, and Adriana Szekeres

Published in: LIPIcs, Volume 281, 37th International Symposium on Distributed Computing (DISC 2023)


Abstract
Traditionally, distributed and parallel transactional systems have been studied in isolation, as they targeted different applications and experienced different bottlenecks. However, modern high-bandwidth networks have made the study of systems that are both distributed (i.e., employ multiple nodes) and parallel (i.e., employ multiple cores per node) necessary to truly make use of the available hardware. In this paper, we study the performance of these combined systems and show that there are inherent tradeoffs between a system’s ability to have fast and robust distributed communication and its ability to scale to multiple cores. More precisely, we formalize the notions of a fast deciding path of communication to commit transactions quickly in good executions, and seamless fault tolerance that allows systems to remain robust to server failures. We then show that there is an inherent tension between these two natural distributed properties and well-known multicore scalability properties in transactional systems. Finally, we show positive results; it is possible to construct a parallel distributed transactional system if any one of the properties we study is removed.

Cite as

Naama Ben-David, Gal Sela, and Adriana Szekeres. The FIDS Theorems: Tensions Between Multinode and Multicore Performance in Transactional Systems. In 37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 9:1-9:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


Copy BibTex To Clipboard

@InProceedings{bendavid_et_al:LIPIcs.DISC.2023.9,
  author =	{Ben-David, Naama and Sela, Gal and Szekeres, Adriana},
  title =	{{The FIDS Theorems: Tensions Between Multinode and Multicore Performance in Transactional Systems}},
  booktitle =	{37th International Symposium on Distributed Computing (DISC 2023)},
  pages =	{9:1--9:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-301-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{281},
  editor =	{Oshman, Rotem},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2023.9},
  URN =		{urn:nbn:de:0030-drops-191355},
  doi =		{10.4230/LIPIcs.DISC.2023.9},
  annote =	{Keywords: transactions, distributed systems, parallel systems, impossibility results}
}
Document
Communication Lower Bounds for Cryptographic Broadcast Protocols

Authors: Erica Blum, Elette Boyle, Ran Cohen, and Chen-Da Liu-Zhang

Published in: LIPIcs, Volume 281, 37th International Symposium on Distributed Computing (DISC 2023)


Abstract
Broadcast protocols enable a set of n parties to agree on the input of a designated sender, even in the face of malicious parties who collude to attack the protocol. In the honest-majority setting, a fruitful line of work harnessed randomization and cryptography to achieve low-communication broadcast protocols with sub-quadratic total communication and with "balanced" sub-linear communication cost per party. However, comparatively little is known in the dishonest-majority setting. Here, the most communication-efficient constructions are based on the protocol of Dolev and Strong (SICOMP '83), and sub-quadratic broadcast has not been achieved even using randomization and cryptography. On the other hand, the only nontrivial ω(n) communication lower bounds are restricted to deterministic protocols, or against strong adaptive adversaries that can perform "after the fact" removal of messages. We provide communication lower bounds in this space, which hold against arbitrary cryptography and setup assumptions, as well as a simple protocol showing near tightness of our first bound. - Static adversary. We demonstrate a tradeoff between resiliency and communication for randomized protocols secure against n-o(n) static corruptions. For example, Ω(n⋅ polylog(n)) messages are needed when the number of honest parties is n/polylog(n); Ω(n√n) messages are needed for O(√n) honest parties; and Ω(n²) messages are needed for O(1) honest parties. Complementarily, we demonstrate broadcast with O(n⋅polylog(n)) total communication and balanced polylog(n) per-party cost, facing any constant fraction of static corruptions. - Weakly adaptive adversary. Our second bound considers n/2 + k corruptions and a weakly adaptive adversary that cannot remove messages "after the fact." We show that any broadcast protocol within this setting can be attacked to force an arbitrary party to send messages to k other parties. Our bound implies limitations on the feasibility of balanced low-communication protocols: For example, ruling out broadcast facing 51% corruptions, in which all non-sender parties have sublinear communication locality.

Cite as

Erica Blum, Elette Boyle, Ran Cohen, and Chen-Da Liu-Zhang. Communication Lower Bounds for Cryptographic Broadcast Protocols. In 37th International Symposium on Distributed Computing (DISC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 281, pp. 10:1-10:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


Copy BibTex To Clipboard

@InProceedings{blum_et_al:LIPIcs.DISC.2023.10,
  author =	{Blum, Erica and Boyle, Elette and Cohen, Ran and Liu-Zhang, Chen-Da},
  title =	{{Communication Lower Bounds for Cryptographic Broadcast Protocols}},
  booktitle =	{37th International Symposium on Distributed Computing (DISC 2023)},
  pages =	{10:1--10:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-301-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{281},
  editor =	{Oshman, Rotem},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2023.10},
  URN =		{urn:nbn:de:0030-drops-191361},
  doi =		{10.4230/LIPIcs.DISC.2023.10},
  annote =	{Keywords: broadcast, communication complexity, lower bounds, dishonest majority}
}
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