,
Guillermo Esteban
,
David Orden
,
Rodrigo I. Silveira
,
Tyler Tuttle
Creative Commons Attribution 4.0 International license
Let Π(n) be the largest number such that for every set S of n points in a polygon P, there always exist two points x, y ∈ S, where every geodesic disk containing x and y contains Π(n) points of S. We establish upper and lower bounds for Π(n), and show that ⌈n/5⌉ +1 ≤ Π(n) ≤ ⌈n/4⌉ +1. We also show that there always exist two points x, y ∈ S such that every geodesic disk with x and y on its boundary contains at least 16/665(n-2) ≈ ⌈(n-2)/41.6⌉ points both inside and outside the disk. For the special case where the points of S are restricted to be the vertices of a geodesically convex polygon we give a tight bound of ⌈n/3⌉ + 1. We provide the same tight bound when we only consider geodesic disks having x and y as diametral endpoints. Finally, we give a lower bound of ⌈(n-2)/36⌉+2 for the two-colored version of the problem.
@InProceedings{bose_et_al:LIPIcs.WADS.2025.10,
author = {Bose, Prosenjit and Esteban, Guillermo and Orden, David and Silveira, Rodrigo I. and Tuttle, Tyler},
title = {{On Geodesic Disks Enclosing Many Points}},
booktitle = {19th International Symposium on Algorithms and Data Structures (WADS 2025)},
pages = {10:1--10:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-398-0},
ISSN = {1868-8969},
year = {2025},
volume = {349},
editor = {Morin, Pat and Oh, Eunjin},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.WADS.2025.10},
URN = {urn:nbn:de:0030-drops-242414},
doi = {10.4230/LIPIcs.WADS.2025.10},
annote = {Keywords: Enclosing disks, Geodesic disks, Bichromatic}
}