,
Heather Newman
,
Kirk Pruhs
Creative Commons Attribution 4.0 International license
We consider the problem in which n points arrive online over time, and upon arrival must be irrevocably assigned to one of k clusters where the objective is the standard k-median objective. Lower-bound instances show that for this problem no online algorithm can achieve a competitive ratio bounded by any function of n. Thus we turn to a beyond worst-case analysis approach, namely we assume that the online algorithm is a priori provided with a predicted budget B that is an upper bound to the optimal objective value (e.g., obtained from past instances). Our main result is an online algorithm whose competitive ratio (measured against B) is solely a function of k. We also give a lower bound showing that the competitive ratio of every algorithm must depend on k.
@InProceedings{moseley_et_al:LIPIcs.APPROX/RANDOM.2024.20,
author = {Moseley, Benjamin and Newman, Heather and Pruhs, Kirk},
title = {{Online k-Median with Consistent Clusters}},
booktitle = {Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2024)},
pages = {20:1--20:22},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-348-5},
ISSN = {1868-8969},
year = {2024},
volume = {317},
editor = {Kumar, Amit and Ron-Zewi, Noga},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.APPROX/RANDOM.2024.20},
URN = {urn:nbn:de:0030-drops-210133},
doi = {10.4230/LIPIcs.APPROX/RANDOM.2024.20},
annote = {Keywords: k-median, online algorithms, learning-augmented algorithms, beyond worst-case analysis}
}