,
Pedro Soto
Creative Commons Attribution 4.0 International license
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).
@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}
}