,
Mark Joachim Krallmann
,
Frank Staals
Creative Commons Attribution 4.0 International license
Let S be a set of n points in R². Our goal is to preprocess S to efficiently compute the smallest enclosing disk of the points in S that lie inside an axis-aligned query rectangle. Previous data structures for this problem achieve a query time of O(log⁶ n) with O(n log² n) preprocessing time and space by lifting the points to 3D, dualizing them into polyhedra, and searching through their intersections. We present a significantly simpler approach, solely based on 2D geometric structures, specifically 2D farthest-point Voronoi diagrams. Our approach achieves a deterministic query time of O(log⁴ n) and, via randomization, an expected query time of O(log^{5/2} n log log n) with the same preprocessing bounds.
@InProceedings{buchin_et_al:LIPIcs.ESA.2026.124,
author = {Buchin, Kevin and Krallmann, Mark Joachim and Staals, Frank},
title = {{Smallest Enclosing Disk Queries Using Farthest-Point Voronoi Diagrams}},
booktitle = {34th Annual European Symposium on Algorithms (ESA 2026)},
pages = {124:1--124:18},
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.2026.124},
URN = {urn:nbn:de:0030-drops-272608},
doi = {10.4230/LIPIcs.ESA.2026.124},
annote = {Keywords: Range searching, smallest enclosing disk, farthest point Voronoi diagram}
}