,
Pierre Fraigniaud
,
Ami Paz
,
Sergio Rajsbaum
Creative Commons Attribution 4.0 International license
The topological view on distributed computing represents a task T as a relation Δ between the complex ℐ of its inputs and the complex 𝒪 of its outputs. A cornerstone result in the field is an elegant computability characterization of the solvability of colorless tasks in terms of ℐ, 𝒪 and Δ. Essentially, a colorless task is wait-free solvable if and only if there is a continuous map from the geometric realization of ℐ to that of 𝒪 that respects Δ. This paper makes headway towards providing an analogous characterization for general tasks, which are not necessarily colorless, by concentrating on the case of three-process inputless tasks. Our key contribution is identifying local articulation points as an obstacle for the solvability of general tasks, and defining a topological deformation on the output complex of a task T, which eliminates these points by splitting them, to obtain a new task T', with an adjusted relation Δ' between the input complex ℐ and an output complex 𝒪' without articulation points. We obtain a new characterization of wait-free solvability of three-process general tasks: T is wait-free solvable if and only if there is a continuous map from the geometric realization of ℐ to that of 𝒪' that respects Δ'.
@InProceedings{attiya_et_al:LIPIcs.DISC.2024.42,
author = {Attiya, Hagit and Fraigniaud, Pierre and Paz, Ami and Rajsbaum, Sergio},
title = {{Brief Announcement: Solvability of Three-Process General Tasks}},
booktitle = {38th International Symposium on Distributed Computing (DISC 2024)},
pages = {42:1--42:7},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-352-2},
ISSN = {1868-8969},
year = {2024},
volume = {319},
editor = {Alistarh, Dan},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2024.42},
URN = {urn:nbn:de:0030-drops-212700},
doi = {10.4230/LIPIcs.DISC.2024.42},
annote = {Keywords: Wait-free computing, lower bounds, topology}
}