,
Hyeonjun Shin
Creative Commons Attribution 4.0 International license
In this paper, we study the problem of constructing a (1/ε)-well-separated pair decomposition (WSPD) for a point set of size n in the Massively Parallel Computation (MPC) model, where multiple machines work in parallel and communicate in synchronous rounds. We present an O(1)-round MPC algorithm that constructs a O(1/ε)-WSPD of size (1/ε)^O(ddim) ⋅ Õ(n) for point sets in a metric space of a constant doubling dimension ddim, with high probability, using (1/ε)^O(ddim) ⋅ Õ(n) total space and O(n^δ) space per machine for a constant δ ∈ (0,1). In the d-dimensional Euclidean space, we can improve the size of the WSPD and the total space to (1/ε)^O(d) n. This improves the best-known algorithm [FOCS'93] for computing a WSPD which requires O(log n) rounds and works only in Euclidean spaces. As a consequence, the following problems can be solved in O(1) rounds in the MPC model: computing a (1+ε)-spanner, a (1-ε)-approximation of the diameter, the closest pair, and the k-nearest neighbors (k-NN). While our k-NN algorithm is specific to Euclidean space, the other three problems can be solved in both Euclidean and doubling metric spaces.
@InProceedings{oh_et_al:LIPIcs.ESA.2026.88,
author = {Oh, Eunjin and Shin, Hyeonjun},
title = {{Fully Scalable MPC Algorithms for WSPD in Doubling and Euclidean Spaces}},
booktitle = {34th Annual European Symposium on Algorithms (ESA 2026)},
pages = {88:1--88:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-445-1},
ISSN = {1868-8969},
year = {2026},
volume = {388},
editor = {Bille, Philip and Pettie, Seth and Storandt, Sabine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2026.88},
URN = {urn:nbn:de:0030-drops-272244},
doi = {10.4230/LIPIcs.ESA.2026.88},
annote = {Keywords: MPC model, parallel algorithms, Computational Geometry, well-separated pair decomposition, doubling metric spaces}
}