conference paper published yes Antoine El-Hayek author 888a098e-fcac-11ee-aff7-d347be57b7250000-0003-4268-7368 Monika H Henzinger author 540c9bbd-f2de-11ec-812d-d04a5be856300000-0002-5008-6530 Stefan Schmid author 0000-0002-7798-1711 YaelTauman Kalai editor ITCS: Innovations in Theoretical Computer Science Data dissemination is a fundamental task in distributed computing. This paper studies broadcast problems in various innovative models where the communication network connecting n processes is dynamic (e.g., due to mobility or failures) and controlled by an adversary. In the first model, the processes transitively communicate their ids in synchronous rounds along a rooted tree given in each round by the adversary whose goal is to maximize the number of rounds until at least one id is known by all processes. Previous research has shown a ⌈(3n-1)/2⌉-2 lower bound and an O(nlog log n) upper bound. We show the first linear upper bound for this problem, namely ⌈(1+√2) n-1⌉ ≈ 2.4n. We extend these results to the setting where the adversary gives in each round k-disjoint forests and their goal is to maximize the number of rounds until there is a set of k ids such that each process knows of at least one of them. We give a ⌈3(n-k)/2⌉-1 lower bound and a (π²+6)/6 n+1 ≈ 2.6n upper bound for this problem. Finally, we study the setting where the adversary gives in each round a directed graph with k roots and their goal is to maximize the number of rounds until there exist k ids that are known by all processes. We give a ⌈3(n-3k)/2⌉+2 lower bound and a ⌈(1+√2)n⌉+k-1 ≈ 2.4n+k upper bound for this problem. For the two latter problems no upper or lower bounds were previously known. https://research-explorer.ista.ac.at/download/22373/22383/2023_LIPIcs_El-Hayek.pdf application/pdfno Schloss Dagstuhl - Leibniz-Zentrum für Informatik2023Cambridge, Massachusetts, USA eng broadcastcoverk-broadcastdynamic radiusdynamic graphsoblivious message adversarytime complexityTheory of computation → Distributed algorithmsNetworks → Network algorithms 1868-8969 9783959772631 2211.1015110.4230/LIPICS.ITCS.2023.47 251 https://research-explorer.ista.ac.at/record/22281 yes El-Hayek A, Henzinger M, Schmid S. 2023. Asymptotically tight bounds on the time complexity of broadcast and its variants in dynamic networks. 14th Innovations in Theoretical Computer Science Conference. ITCS: Innovations in Theoretical Computer Science, LIPIcs, vol. 251, 47. A. El-Hayek, M. Henzinger, S. Schmid, in:, Y. Tauman Kalai (Ed.), 14th Innovations in Theoretical Computer Science Conference, Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2023. El-Hayek, Antoine, Monika Henzinger, and Stefan Schmid. “Asymptotically Tight Bounds on the Time Complexity of Broadcast and Its Variants in Dynamic Networks.” In <i>14th Innovations in Theoretical Computer Science Conference</i>, edited by Yael Tauman Kalai, Vol. 251. Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2023. <a href="https://doi.org/10.4230/LIPICS.ITCS.2023.47">https://doi.org/10.4230/LIPICS.ITCS.2023.47</a>. El-Hayek, Antoine, et al. “Asymptotically Tight Bounds on the Time Complexity of Broadcast and Its Variants in Dynamic Networks.” <i>14th Innovations in Theoretical Computer Science Conference</i>, edited by Yael Tauman Kalai, vol. 251, 47, Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2023, doi:<a href="https://doi.org/10.4230/LIPICS.ITCS.2023.47">10.4230/LIPICS.ITCS.2023.47</a>. El-Hayek A, Henzinger M, Schmid S. Asymptotically tight bounds on the time complexity of broadcast and its variants in dynamic networks. In: Tauman Kalai Y, ed. <i>14th Innovations in Theoretical Computer Science Conference</i>. Vol 251. Schloss Dagstuhl - Leibniz-Zentrum für Informatik; 2023. doi:<a href="https://doi.org/10.4230/LIPICS.ITCS.2023.47">10.4230/LIPICS.ITCS.2023.47</a> A. El-Hayek, M. Henzinger, and S. Schmid, “Asymptotically tight bounds on the time complexity of broadcast and its variants in dynamic networks,” in <i>14th Innovations in Theoretical Computer Science Conference</i>, Cambridge, Massachusetts, USA, 2023, vol. 251. El-Hayek, A., Henzinger, M., &#38; Schmid, S. (2023). Asymptotically tight bounds on the time complexity of broadcast and its variants in dynamic networks. In Y. Tauman Kalai (Ed.), <i>14th Innovations in Theoretical Computer Science Conference</i> (Vol. 251). Cambridge, Massachusetts, USA: Schloss Dagstuhl - Leibniz-Zentrum für Informatik. <a href="https://doi.org/10.4230/LIPICS.ITCS.2023.47">https://doi.org/10.4230/LIPICS.ITCS.2023.47</a> 223732026-07-20T11:45:04Z2026-07-24T12:48:29Z