,
Antonis Skarlatos
Creative Commons Attribution 4.0 International license
In the incremental consistent k-center clustering problem, we are given a sequence of adversarial point insertions and aim to maintain a k-center solution with small approximation ratio and small recourse. In this work, we explore the following question: what is the best approximation ratio of a polynomial-time algorithm with a worst-case recourse of 1? Our result improves upon the 6-approximation algorithm of Forster and Skarlatos [SODA '25], which itself improved over the 8-approximation algorithm of Charikar, Chekuri, Feder, and Motwani [STOC '97]. Moreover, we show that any incremental k-center algorithm that achieves an approximation ratio strictly less than √ 2 requires a worst-case recourse of k.
@InProceedings{grilnberger_et_al:LIPIcs.APPROX/RANDOM.2026.29,
author = {Grilnberger, Mara and Skarlatos, Antonis},
title = {{Incremental Consistent k-Center Clustering}},
booktitle = {Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2026)},
pages = {29:1--29:19},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-449-9},
ISSN = {1868-8969},
year = {2026},
volume = {392},
editor = {Singh, Mohit and Gur, Tom},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.APPROX/RANDOM.2026.29},
URN = {urn:nbn:de:0030-drops-277466},
doi = {10.4230/LIPIcs.APPROX/RANDOM.2026.29},
annote = {Keywords: Consistent Clustering, k-Center, Dynamic Algorithms}
}