,
Ameet Gadekar
Creative Commons Attribution 4.0 International license
The Capacitated Sum of Radii problem involves partitioning a set of points P, where each point p ∈ P has capacity U_p, into k clusters that minimize the sum of cluster radii, such that the number of points in the cluster centered at point p is at most U_p. We begin by showing that the problem is APX-hard, and that under gap-ETH there is no parameterized approximation scheme (FPT-AS). We then construct a ≈5.83-approximation algorithm in FPT time (improving a previous ≈7.61 approximation in FPT time). Our results also hold when the objective is a general monotone symmetric norm of radii. We also improve the approximation factors for the uniform capacity case, and for the closely related problem of Capacitated Sum of Diameters.
@InProceedings{filtser_et_al:LIPIcs.SoCG.2026.48,
author = {Filtser, Arnold and Gadekar, Ameet},
title = {{FPT Approximations for Capacitated Sum of Radii and Diameters}},
booktitle = {42nd International Symposium on Computational Geometry (SoCG 2026)},
pages = {48:1--48:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-418-5},
ISSN = {1868-8969},
year = {2026},
volume = {367},
editor = {Ahn, Hee-Kap and Hoffmann, Michael and Nayyeri, Amir},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2026.48},
URN = {urn:nbn:de:0030-drops-258545},
doi = {10.4230/LIPIcs.SoCG.2026.48},
annote = {Keywords: clustering, sum of radii, sum of diameter, capacitated clustering, fpt}
}