92 Search Results for "Lynch, Nancy"

Artifact
Software
DOI: 10.4230/artifacts.26614
Nanobot Algorithms for Multi-Site Cancer Detection and Treatment, Model/Simulator

Authors: Noble Harasha

Abstract
Cite as

Noble Harasha. Nanobot Algorithms for Multi-Site Cancer Detection and Treatment, Model/Simulator (Software, Base Simulation Code). Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@misc{code,
   title = {{Nanobot Algorithms for Multi-Site Cancer Detection and Treatment, Model/Simulator}}, 
   author = {Harasha, Noble},
   note = {Software, swhId: \href{https://archive.softwareheritage.org/swh:1:dir:28c094aedd1ef8a44141bb42b5b2ae1d98ab89cc;origin=https://github.com/nobleharasha/nanobots-multiSite-ctsSim;visit=swh:1:snp:3ee6db28331709cbb87b598bba40b53eed7f4970;anchor=swh:1:rev:18608986842f36f0ea8a6dc70340b74058641250}{\texttt{swh:1:dir:28c094aedd1ef8a44141bb42b5b2ae1d98ab89cc}} (visited on 2026-06-24)},
   url = {https://github.com/nobleharasha/nanobots-multiSite-ctsSim/},
   doi = {10.4230/artifacts.26614},
}
Document
DOI: 10.4230/LIPIcs.SAND.2026.12
Nanobot Algorithms for Treatment of Diffuse Cancer

Authors: Noble C. Harasha and Nancy Lynch

Published in: LIPIcs, Volume 373, 5th Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2026)

Abstract
We consider the problem of a swarm of nanobots detecting and treating human cancer that is diffuse, that is, dispersed in a region with multiple separate cancer sites in need of treatment. We present a mathematical model of nanobots and their colloidal environment that is inspired by actual chemotactic nanoparticles, involving agents noisily following chemical gradients (both attractively and repellently, depending on the chemical). We present three incrementally sophisticated algorithms that describe additional chemical payloads that agents carry onboard, beyond the cancer-treating drug K, as well as the rules for when agents drop their payloads: Algorithm KM, in which agents simply ascend naturally existing chemical M signals that surround cancer sites; Algorithm KMA, in which agents themselves amplify these natural signals by dropping chemical A payloads upon reaching a site; and Algorithm KMAR, in which agents choose to either amplify the signal by dropping chemical A or counteract/reduce the signal by dropping chemical R, according to the current unsatisfied demand of the site. We present simulation results for all of the algorithms, across a set of distinct cancer arrangements, that track both the achieved treatment success as well as the time/duration of the treatment. KM has generally successful treatment unless the natural M-signals are weak, in which case the treatment progresses too slowly. KMA demonstrates a significant speedup in treatment time (over KM), but also a drop in success except for the most concentrated cancer patterns. KMAR has relatively optimal performance across all types of cancer patterns, demonstrating robustness and adaptability in its mechanisms for nanobot coordination.
Cite as

Noble C. Harasha and Nancy Lynch. Nanobot Algorithms for Treatment of Diffuse Cancer. In 5th Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 373, pp. 12:1-12:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{harasha_et_al:LIPIcs.SAND.2026.12,
  author =	{Harasha, Noble C. and Lynch, Nancy},
  title =	{{Nanobot Algorithms for Treatment of Diffuse Cancer}},
  booktitle =	{5th Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2026)},
  pages =	{12:1--12:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-427-7},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{373},
  editor =	{Mertzios, George B. and Richa, Andr\'{e}a W.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAND.2026.12},
  URN =		{urn:nbn:de:0030-drops-262469},
  doi =		{10.4230/LIPIcs.SAND.2026.12},
  annote =	{Keywords: Nanobots, biological modeling, distributed algorithms, agent-based models, random walks, cancer detection, cancer treatment}
}
Document
DOI: 10.4230/LIPIcs.SWAT.2026.30
Parallel Algorithms for Group Isomorphism via Code Equivalence

Authors: Michael Levet

Published in: LIPIcs, Volume 370, 20th Scandinavian Symposium on Algorithm Theory (SWAT 2026)

Abstract
In this paper, we exhibit AC³ isomorphism tests for coprime extensions H ⋉ N where H is elementary Abelian and N is Abelian; and groups where Rad(G) = Z(G) is elementary Abelian and G = Soc^{*}(G). The fact that isomorphism testing for these families is in P was established respectively by Qiao, Sarma, and Tang (STACS 2011), and Grochow and Qiao (CCC 2014, SIAM J. Comput. 2017). The polynomial-time isomorphism tests for both of these families crucially leveraged small (size O(log |G|)) instances of Linear Code Equivalence (Babai, SODA 2011). Here, we combine Luks' group-theoretic method for Graph Isomorphism (FOCS 1980, J. Comput. Syst. Sci. 1982) with the fact that G is given by its multiplication table, to implement the corresponding instances of Linear Code Equivalence in AC³. As a byproduct of our work, we show that isomorphism testing of arbitrary central-radical groups is decidable using AC circuits of depth O(log³ n) and size n^{O(log log n)}. This improves upon the previous bound of n^{O(log log n)}-time due to Grochow and Qiao (ibid.).
Cite as

Michael Levet. Parallel Algorithms for Group Isomorphism via Code Equivalence. In 20th Scandinavian Symposium on Algorithm Theory (SWAT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 370, pp. 30:1-30:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{levet:LIPIcs.SWAT.2026.30,
  author =	{Levet, Michael},
  title =	{{Parallel Algorithms for Group Isomorphism via Code Equivalence}},
  booktitle =	{20th Scandinavian Symposium on Algorithm Theory (SWAT 2026)},
  pages =	{30:1--30:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-421-5},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{370},
  editor =	{Fraigniaud, Pierre},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SWAT.2026.30},
  URN =		{urn:nbn:de:0030-drops-260660},
  doi =		{10.4230/LIPIcs.SWAT.2026.30},
  annote =	{Keywords: Group Isomorphism, Circuit Complexity, Code Equivalence}
}
Document
DOI: 10.4230/LIPIcs.FUN.2026.10
77 Shades of Grey

Authors: Quentin Bramas, Stéphane Devismes, Anaïs Durand, Pascal Lafourcade, and Anissa Lamani

Published in: LIPIcs, Volume 366, 13th International Conference on Fun with Algorithms (FUN 2026)

Abstract
Bruce Wayne contacted us to help him develop a new surveillance technology for dark environments such as caves, using a swarm of Unmanned Aerial Vehicles (UAVs), called Batdroids. A Batdroid has no chirality, limited visibility, and a perfect clock to synchronize with the others. A Batdroid can produce 77 shades of grey in dark mode and four colors in light mode. In this paper, we propose two algorithms using three Batdroids to perpetually explore a finite 3D grid modeling a cave. The first algorithm operates in darkness, uses 77 shades of grey, and requires visibility range one. The second operates in light, uses four colors and visibility range two. We also prove that three is the optimal number of Batdroids required to solve Bruce Wayne’s challenge.
Cite as

Quentin Bramas, Stéphane Devismes, Anaïs Durand, Pascal Lafourcade, and Anissa Lamani. 77 Shades of Grey. In 13th International Conference on Fun with Algorithms (FUN 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 366, pp. 10:1-10:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{bramas_et_al:LIPIcs.FUN.2026.10,
  author =	{Bramas, Quentin and Devismes, St\'{e}phane and Durand, Ana\"{i}s and Lafourcade, Pascal and Lamani, Anissa},
  title =	{{77 Shades of Grey}},
  booktitle =	{13th International Conference on Fun with Algorithms (FUN 2026)},
  pages =	{10:1--10:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-417-8},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{366},
  editor =	{Iacono, John},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FUN.2026.10},
  URN =		{urn:nbn:de:0030-drops-257294},
  doi =		{10.4230/LIPIcs.FUN.2026.10},
  annote =	{Keywords: Mobile robots, grid exploration, perpetual exploration}
}
Document
DOI: 10.4230/OASIcs.NINeS.2026.3
Limix: Limiting Lamport Exposure to Distant Failures in Globally-Managed Distributed Systems

Authors: Cristina Băsescu, Georgia Fragkouli, Enis Ceyhun Alp, Michael F. Nowlan, Jose M. Faleiro, Gaylor Bosson, Kelong Cong, Pierluca Borsò-Tan, Vero Estrada-Galiñanes, and Bryan Ford

Published in: OASIcs, Volume 139, 1st New Ideas in Networked Systems (NINeS 2026)

Abstract
Globalized computing infrastructures offer the convenience and elasticity of globally managed objects and services, but lack the resilience to distant failures that localized infrastructures such as private clouds provide. Providing both global management and resilience to distant failures, however, poses a fundamental problem for configuration services: How to discover a possibly migratory, strongly-consistent service/object in a globalized infrastructure without dependencies on globalized state? Limix is the first metadata configuration service that addresses this problem. With Limix, global strongly-consistent data-plane services and objects are insulated from remote gray failures by ensuring that the definitive, strongly-consistent metadata for any object is always confined to the same region as the object itself. Limix guarantees availability bounds: any user can continue accessing any strongly consistent object that matters to the user located at distance Δ away, insulated from failures outside a small multiple of Δ. We built a Limix metadata service based on the key-value interface of CockroachDB. Our experiments on Internet-like networks and on AWS, using realistic trace-driven workloads, show that Limix enables global management and significantly improves availability over the state-of-the-art.
Cite as

Cristina Băsescu, Georgia Fragkouli, Enis Ceyhun Alp, Michael F. Nowlan, Jose M. Faleiro, Gaylor Bosson, Kelong Cong, Pierluca Borsò-Tan, Vero Estrada-Galiñanes, and Bryan Ford. Limix: Limiting Lamport Exposure to Distant Failures in Globally-Managed Distributed Systems. In 1st New Ideas in Networked Systems (NINeS 2026). Open Access Series in Informatics (OASIcs), Volume 139, pp. 3:1-3:29, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{basescu_et_al:OASIcs.NINeS.2026.3,
  author =	{B\u{a}sescu, Cristina and Fragkouli, Georgia and Alp, Enis Ceyhun and Nowlan, Michael F. and Faleiro, Jose M. and Bosson, Gaylor and Cong, Kelong and Bors\`{o}-Tan, Pierluca and Estrada-Gali\~{n}anes, Vero and Ford, Bryan},
  title =	{{Limix: Limiting Lamport Exposure to Distant Failures in Globally-Managed Distributed Systems}},
  booktitle =	{1st New Ideas in Networked Systems (NINeS 2026)},
  pages =	{3:1--3:29},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-414-7},
  ISSN =	{2190-6807},
  year =	{2026},
  volume =	{139},
  editor =	{Argyraki, Katerina and Panda, Aurojit},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.NINeS.2026.3},
  URN =		{urn:nbn:de:0030-drops-255880},
  doi =		{10.4230/OASIcs.NINeS.2026.3},
  annote =	{Keywords: Distributed systems, Availability, Fault tolerance, Strong-consistency, Coordination systems, Lamport exposure}
}
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.OPODIS.2025.7
Mobile Byzantine Agreement in a Trusted World

Authors: Bo Pan and Maria Potop-Butucaru

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

Abstract
In this paper, we address the Byzantine Agreement problem in synchronous systems where Byzantine agents can move from process to process, corrupting their host. We focus on two representative models: Garay’s and Buhrman’s models. In Garay’s model, when a process has been left by the Byzantine agent, it enters a cured state, is aware of its condition, and can remain silent for a round to prevent the dissemination of incorrect information. In Buhrman’s model, a Byzantine agent moves together with the message. It has been shown that solving Byzantine Agreement requires at least 4t + 1 processes in Garay’s model, and at least 3t + 1 in Buhrman’s model. In this paper, we aim to increase the tolerance to mobile Byzantine agents by integrating a trusted counter abstraction into both models. This abstraction prevents nodes from equivocating. In the new models, we prove that at least 3t+1, respectively 2t+1 processors are needed to tolerate t mobile Byzantine agents. Furthermore, we propose novel Mobile Byzantine Agreement algorithms that match these new lower bounds for both Garay’s and Buhrman’s models, achieving agreement in 𝒪(n) synchronous rounds.
Cite as

Bo Pan and Maria Potop-Butucaru. Mobile Byzantine Agreement in a Trusted World. In 29th International Conference on Principles of Distributed Systems (OPODIS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 361, pp. 7:1-7:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

Copy BibTex To Clipboard

@InProceedings{pan_et_al:LIPIcs.OPODIS.2025.7,
  author =	{Pan, Bo and Potop-Butucaru, Maria},
  title =	{{Mobile Byzantine Agreement in a Trusted World}},
  booktitle =	{29th International Conference on Principles of Distributed Systems (OPODIS 2025)},
  pages =	{7:1--7:20},
  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.2025.7},
  URN =		{urn:nbn:de:0030-drops-251809},
  doi =		{10.4230/LIPIcs.OPODIS.2025.7},
  annote =	{Keywords: Byzantine Agreement, Mobile Faults, Trusted Abstractions}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2025.8
Weaker Assumptions for Asymmetric Trust

Authors: Ignacio Amores-Sesar, Christian Cachin, Simon Holmgaard Kamp, and Juan Villacis

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

Abstract
In distributed systems with asymmetric trust, each participant is free to make its own trust assumptions about others, captured by an asymmetric quorum system. This contrasts with ordinary, symmetric quorum systems and threshold models, where trust assumptions are uniformly shared among participants. Fundamental problems like reliable broadcast and consensus are unsolvable in the asymmetric model if quorum systems satisfy only the classical properties of consistency and availability. Existing approaches overcome this by introducing stronger assumptions. We show that some of these assumptions are overly restrictive, so much so that they effectively eliminate the benefits of asymmetric trust. To address this, we propose a new approach to characterize asymmetric problems and, building upon it, present algorithms for reliable broadcast and consensus that require weaker assumptions than previous solutions. Our methods are general and can be extended to other core problems in systems with asymmetric trust.
Cite as

Ignacio Amores-Sesar, Christian Cachin, Simon Holmgaard Kamp, and Juan Villacis. Weaker Assumptions for Asymmetric Trust. In 29th International Conference on Principles of Distributed Systems (OPODIS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 361, pp. 8:1-8:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

Copy BibTex To Clipboard

@InProceedings{amoressesar_et_al:LIPIcs.OPODIS.2025.8,
  author =	{Amores-Sesar, Ignacio and Cachin, Christian and Kamp, Simon Holmgaard and Villacis, Juan},
  title =	{{Weaker Assumptions for Asymmetric Trust}},
  booktitle =	{29th International Conference on Principles of Distributed Systems (OPODIS 2025)},
  pages =	{8:1--8:18},
  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.2025.8},
  URN =		{urn:nbn:de:0030-drops-251812},
  doi =		{10.4230/LIPIcs.OPODIS.2025.8},
  annote =	{Keywords: Asymmetric Trust, Quorum Systems, Reliable Broadcast, Consensus}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2025.9
Contention-Aware Cooperation

Authors: Timothé Albouy, Davide Frey, Mathieu Gestin, Michel Raynal, and François Taïani

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

Abstract
As shown by Reliable Broadcast and Consensus, cooperation among a set of independent computing entities (sequential processes) is crucial in fault-tolerant distributed computing. Considering n-process asynchronous message-passing systems where some processes may be Byzantine, this paper introduces a novel cooperation abstraction, Contention-Aware Cooperation (CAC). While Reliable Broadcast is a one-to-n cooperation abstraction and Consensus is an n-to-n cooperation abstraction, CAC is a d-to-n cooperation abstraction where d (1 ≤ d ≤ n) varies with each run and remains unknown to the processes. Correct processes accept the same set of 𝓁 pairs ⟨ v,i ⟩ (v is the value proposed by p_i) from the d proposer processes, where 1 ≤ 𝓁 ≤ d and (as d) 𝓁 remains unknown to the processes (except in specific cases). Those 𝓁 values are accepted one at a time, potentially in different orders at each process. In addition, CAC provides each process with an imperfect oracle that provides insights into the values that they may accept in the future. Interestingly, the CAC abstraction is particularly efficient in favorable circumstances, when the oracle becomes accurate, which processes can detect. To illustrate its practical utility, the paper details two applications leveraging CAC: a fast consensus implementation optimized for low contention (named Cascading Consensus), and a novel naming problem that can be solved under full asynchrony. All algorithms presented require signatures.
Cite as

Timothé Albouy, Davide Frey, Mathieu Gestin, Michel Raynal, and François Taïani. Contention-Aware Cooperation. In 29th International Conference on Principles of Distributed Systems (OPODIS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 361, pp. 9:1-9:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

Copy BibTex To Clipboard

@InProceedings{albouy_et_al:LIPIcs.OPODIS.2025.9,
  author =	{Albouy, Timoth\'{e} and Frey, Davide and Gestin, Mathieu and Raynal, Michel and Ta\"{i}ani, Fran\c{c}ois},
  title =	{{Contention-Aware Cooperation}},
  booktitle =	{29th International Conference on Principles of Distributed Systems (OPODIS 2025)},
  pages =	{9:1--9:19},
  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.2025.9},
  URN =		{urn:nbn:de:0030-drops-251823},
  doi =		{10.4230/LIPIcs.OPODIS.2025.9},
  annote =	{Keywords: Agreement, Asynchronous message-passing system, Byzantine processes, Conflict detection, Consensus, Cooperation abstraction, Distributed computing, Fault tolerance, Optimistically terminating consensus, Short-naming}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2025.10
Computing in a Faulty Congested Clique

Authors: Keren Censor-Hillel and Pedro Soto

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

Abstract
We study a Faulty Congested Clique model, in which an adversary may fail nodes in the network throughout the computation. We show that any task of O(nlog{n})-bit input per node can be solved in roughly n rounds, where n is the size of the network. This nearly matches the linear upper bound on the complexity of the non-faulty Congested Clique model for such problems, by learning the entire input, and it holds in the faulty model even with a linear number of faults. Our main contribution is that we establish that one can do much better by looking more closely at the computation. Given a deterministic algorithm 𝒜 for the non-faulty Congested Clique model, we show how to transform it into an algorithm 𝒜' for the faulty model, with an overhead that could be as small as some logarithmic-in-n factor, by considering refined complexity measures of 𝒜. As an exemplifying application of our approach, we show that the O(n^{1/3})-round complexity of semi-ring matrix multiplication [Censor{-}Hillel, Kaski, Korhonen, Lenzen, Paz, Suomela, PODC 2015] remains the same up to polylog factors in the faulty model, even if the adversary can fail 99% of the nodes (or any other constant fraction).
Cite as

Keren Censor-Hillel and Pedro Soto. Computing in a Faulty Congested Clique. In 29th International Conference on Principles of Distributed Systems (OPODIS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 361, pp. 10:1-10:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

Copy BibTex To Clipboard

@InProceedings{censorhillel_et_al:LIPIcs.OPODIS.2025.10,
  author =	{Censor-Hillel, Keren and Soto, Pedro},
  title =	{{Computing in a Faulty Congested Clique}},
  booktitle =	{29th International Conference on Principles of Distributed Systems (OPODIS 2025)},
  pages =	{10:1--10:19},
  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.2025.10},
  URN =		{urn:nbn:de:0030-drops-251833},
  doi =		{10.4230/LIPIcs.OPODIS.2025.10},
  annote =	{Keywords: distributed computing, graph algorithms, computing with faults}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2025.11
Formalizing Rollback Netcodes for Robust and Real-Time Client-Server Architectures

Authors: Yérom-David Bromberg, Jérémie Decouchant, Manon Sourisseau, and François Taïani

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

Abstract
The rapid growth of the gaming industry has made netcodes (the part of an online game’s source code that handles networking and synchronization) a critical component of the online multiplayer experience. Among various approaches, rollback netcodes have become a popular choice for real-time games due to their ability to enhance responsiveness and player immersion. However, despite their widespread adoption, these netcodes remain susceptible to subtle latency-based attacks that can be challenging to detect. Notably, while rollback netcodes play a critical role in the gaming industry and share similarities with synchronization mechanisms in distributed systems, they have received relatively limited attention in academic research. In this work, we present a formal specification of rollback netcodes and identify key behavioral properties and requirements to strengthen their resilience against latency-based attacks that are prevalent in gaming, such as lag-switch and DDoS attacks. Our analysis allows us to explore the trade-offs between preserving immersive gameplay and ensuring security. Our findings reveal that ideal immersion requires strict assumptions about network latency, which are unattainable in adversarial environments where message delays are inevitable.
Cite as

Yérom-David Bromberg, Jérémie Decouchant, Manon Sourisseau, and François Taïani. Formalizing Rollback Netcodes for Robust and Real-Time Client-Server Architectures. In 29th International Conference on Principles of Distributed Systems (OPODIS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 361, pp. 11:1-11:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

Copy BibTex To Clipboard

@InProceedings{bromberg_et_al:LIPIcs.OPODIS.2025.11,
  author =	{Bromberg, Y\'{e}rom-David and Decouchant, J\'{e}r\'{e}mie and Sourisseau, Manon and Ta\"{i}ani, Fran\c{c}ois},
  title =	{{Formalizing Rollback Netcodes for Robust and Real-Time Client-Server Architectures}},
  booktitle =	{29th International Conference on Principles of Distributed Systems (OPODIS 2025)},
  pages =	{11:1--11:17},
  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.2025.11},
  URN =		{urn:nbn:de:0030-drops-251841},
  doi =		{10.4230/LIPIcs.OPODIS.2025.11},
  annote =	{Keywords: Online Multiplayer Game, Rollback Netcode, Network Security, Latency attacks}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2025.15
Time-Optimal and Energy-Efficient Deterministic Consensus

Authors: Shachar Meir, Hugo Mirault, David Peleg, and Peter Robinson

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

Abstract
We study fault-tolerant consensus in a variant of the synchronous message passing model, where, in each round, every node can choose to be awake or asleep. This is known as the sleeping model (Chatterjee, Gmyr, Pandurangan PODC 2020) and defines the awake complexity (also called energy complexity), which measures the maximum number of rounds that any node is awake throughout the execution. Only awake nodes can send and receive messages in a given round and all messages sent to sleeping nodes are lost. We present new deterministic consensus algorithms that tolerate up to f < n crash failures, where n is the number of nodes. Our algorithms match the optimal time complexity lower bound of f+1 rounds. For multi-value consensus, where the input values are chosen from some possibly large set, we achieve an energy complexity of 𝒪(⌈ f² / n ⌉) rounds, whereas for binary consensus, we show an algorithm to achieve 𝒪(⌈ f / √n ⌉) energy complexity.
Cite as

Shachar Meir, Hugo Mirault, David Peleg, and Peter Robinson. Time-Optimal and Energy-Efficient Deterministic Consensus. In 29th International Conference on Principles of Distributed Systems (OPODIS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 361, pp. 15:1-15:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

Copy BibTex To Clipboard

@InProceedings{meir_et_al:LIPIcs.OPODIS.2025.15,
  author =	{Meir, Shachar and Mirault, Hugo and Peleg, David and Robinson, Peter},
  title =	{{Time-Optimal and Energy-Efficient Deterministic Consensus}},
  booktitle =	{29th International Conference on Principles of Distributed Systems (OPODIS 2025)},
  pages =	{15:1--15:16},
  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.2025.15},
  URN =		{urn:nbn:de:0030-drops-251881},
  doi =		{10.4230/LIPIcs.OPODIS.2025.15},
  annote =	{Keywords: Distributed computing, Crash faults, Consensus, Energy complexity, Sleeping model}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2025.18
Distributed Download from an External Data Source in Asynchronous Faulty Settings

Authors: John Augustine, Soumyottam Chatterjee, Valerie King, Manish Kumar, Shachar Meir, and David Peleg

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

Abstract
The distributed Data Retrieval (DR) model consists of k peers connected by a complete peer-to-peer communication network, and a trusted external data source that stores an array X of n bits (n ≫ k). Up to β k of the peers might fail in any execution (for β ∈ [0, 1)). Peers can obtain the information either by inexpensive messages passed among themselves or through expensive queries to the source array X. In the DR model, we focus on designing protocols that minimize the number of queries performed by any nonfaulty peer (a measure referred to as the query complexity) while maximizing the resiliency parameter β. The Download problem requires each nonfaulty peer to correctly learn the entire array X. Earlier work on this problem focused on synchronous communication networks and established several deterministic and randomized upper and lower bounds. Our work is the first to extend the study of distributed data retrieval to asynchronous communication networks. We address the Download problem under both the Byzantine and crash failure models. We present query-optimal deterministic solutions in an asynchronous model that can tolerate any fixed fraction β < 1 of crash faults. In the Byzantine failure model, it is known that deterministic protocols incur a query complexity of Ω(n) per peer, even under synchrony. We extend this lower bound to randomized protocols in the asynchronous model for β ≥ 1/2, and further show that for β < 1/2, a randomized protocol exists with near-optimal query complexity.
Cite as

John Augustine, Soumyottam Chatterjee, Valerie King, Manish Kumar, Shachar Meir, and David Peleg. Distributed Download from an External Data Source in Asynchronous Faulty Settings. In 29th International Conference on Principles of Distributed Systems (OPODIS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 361, pp. 18:1-18:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

Copy BibTex To Clipboard

@InProceedings{augustine_et_al:LIPIcs.OPODIS.2025.18,
  author =	{Augustine, John and Chatterjee, Soumyottam and King, Valerie and Kumar, Manish and Meir, Shachar and Peleg, David},
  title =	{{Distributed Download from an External Data Source in Asynchronous Faulty Settings}},
  booktitle =	{29th International Conference on Principles of Distributed Systems (OPODIS 2025)},
  pages =	{18:1--18:17},
  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.2025.18},
  URN =		{urn:nbn:de:0030-drops-251915},
  doi =		{10.4230/LIPIcs.OPODIS.2025.18},
  annote =	{Keywords: Byzantine Fault Tolerance, Blockchain Oracle, Data Retrieval Model, Distributed Download, asynchrony}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2025.16
Asynchronous Approximate Agreement with Quadratic Communication

Authors: Mose Mizrahi Erbes and Roger Wattenhofer

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

Abstract
We study approximate agreement in an asynchronous network of n parties, up to t of which are byzantine. This an agreement task where the parties obtain approximately equal inputs in the convex hull of their inputs. In an asynchronous network, it can be solved with the optimal resilience t < n/3 by forcing the parties to reliably broadcast their messages and thus preventing inconsistent byzantine behavior. This costs Θ(n²) messages per reliable broadcast, or Θ(n³) messages per protocol iteration. In this work, we forgo reliable broadcast to achieve asynchronous approximate agreement against t < n/3 faults with quadratic communication. In a tree with the maximum degree Δ and the centroid decomposition height h, we achieve edge agreement (agreement on two adjacent vertices) in at most 6h + 1 rounds with 𝒪(n²) messages of size 𝒪(log Δ + log h) per round. We do this by designing a 6-round multivalued 2-graded consensus protocol and using it to construct a recursive edge agreement protocol. Then, we achieve edge agreement in the infinite path ℤ, again by using 2-graded consensus. Finally, we show that our edge agreement protocol enables approximate agreement in ℝ (with outputs that are at most some small parameter ε > 0 apart) in 6log₂M/(ε) + 𝒪(log log M/(ε)) rounds with 𝒪(n²) messages of size 𝒪(log log M/(ε)) per round, where M is the maximum non-byzantine input magnitude.
Cite as

Mose Mizrahi Erbes and Roger Wattenhofer. Asynchronous Approximate Agreement with Quadratic Communication. In 29th International Conference on Principles of Distributed Systems (OPODIS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 361, pp. 16:1-16:26, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

Copy BibTex To Clipboard

@InProceedings{mizrahierbes_et_al:LIPIcs.OPODIS.2025.16,
  author =	{Mizrahi Erbes, Mose and Wattenhofer, Roger},
  title =	{{Asynchronous Approximate Agreement with Quadratic Communication}},
  booktitle =	{29th International Conference on Principles of Distributed Systems (OPODIS 2025)},
  pages =	{16:1--16:26},
  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.2025.16},
  URN =		{urn:nbn:de:0030-drops-251890},
  doi =		{10.4230/LIPIcs.OPODIS.2025.16},
  annote =	{Keywords: Approximate agreement, byzantine fault tolerance, communication complexity}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2025.24
On Time-Optimal, Fault-Tolerant Algorithms for Connected Consensus Beyond Grade Two

Authors: Alan Ernesto Arteaga Vázquez

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

Abstract
A common question in the asynchronous model is whether some given notion of agreement between processes is achievable. Usually, we formalise such agreement notions in the form of agreement problems. Some of these problems also receive the name of coordination primitives. Several fault-tolerant algorithms in asynchronous systems rely upon the use of different primitives as building blocks, such as adopt-commit, crusader agreement, or graded broadcast. Recently, the connected consensus problem - a form of agreement over a specific family of graphs parametrised by a positive integer R- was introduced. This problem unifies the three mentioned primitives while extending them for multi-valued inputs. Moreover, the problem is equipped with a security condition called binding, which limits the effect of malicious processes over the decision of correct parties. While fault-tolerant connected consensus algorithms for R = 1 and R = 2 are known, the existence of algorithmic solutions for any positive integer parameter remained an open question. In this work, we introduce a pair of fault-tolerant algorithms for connected consensus when the R parameter is any positive integer. We introduce a crash-resilient algorithm, which is optimal with respect to the maximum number of possible faulty processes. Our second algorithm is resilient to Byzantine failures; whose failure-resilience is optimal for a specific class of algorithms. Both algorithms satisfy the binding property and match the best known time complexities achieved for the R = 1 and R = 2 cases, further achieving time optimality for the general case in the crash-failure setting, and asymptotic time optimality in the Byzantine scenario.
Cite as

Alan Ernesto Arteaga Vázquez. On Time-Optimal, Fault-Tolerant Algorithms for Connected Consensus Beyond Grade Two. In 29th International Conference on Principles of Distributed Systems (OPODIS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 361, pp. 24:1-24:28, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

Copy BibTex To Clipboard

@InProceedings{arteagavazquez:LIPIcs.OPODIS.2025.24,
  author =	{Arteaga V\'{a}zquez, Alan Ernesto},
  title =	{{On Time-Optimal, Fault-Tolerant Algorithms for Connected Consensus Beyond Grade Two}},
  booktitle =	{29th International Conference on Principles of Distributed Systems (OPODIS 2025)},
  pages =	{24:1--24:28},
  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.2025.24},
  URN =		{urn:nbn:de:0030-drops-251973},
  doi =		{10.4230/LIPIcs.OPODIS.2025.24},
  annote =	{Keywords: Approximate Agreement, Binding, Connected Consensus}
}
  • Refine by Type
  • 91 Document/PDF
  • 75 Document/HTML
  • 1 Artifact

  • Refine by Publication Year
  • 19 2026
  • 58 2025
  • 3 2022
  • 3 2020
  • 2 2019
  • Show More...

  • Refine by Author
  • 10 Lynch, Nancy
  • 5 Kutten, Shay
  • 5 Wattenhofer, Roger
  • 4 Kowalski, Dariusz R.
  • 3 Albouy, Timothé
  • Show More...

  • Refine by Series/Journal
  • 84 LIPIcs
  • 4 OASIcs
  • 2 LITES
  • 1 DagSemProc

  • Refine by Classification
  • 43 Theory of computation → Distributed algorithms
  • 10 Theory of computation → Distributed computing models
  • 8 Security and privacy → Distributed systems security
  • 5 Computer systems organization → Dependable and fault-tolerant systems and networks
  • 4 Computing methodologies → Distributed algorithms
  • Show More...

  • Refine by Keyword
  • 7 Consensus
  • 5 Blockchain
  • 3 Approximate agreement
  • 3 Byzantine Agreement
  • 3 Byzantine Fault Tolerance
  • 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