,
Maike Buchin
,
Joachim Gudmundsson
,
Sampson Wong
Creative Commons Attribution 4.0 International license
Spanner constructions focus on the initial design of the network. However, networks tend to improve over time. In this paper, we focus on the improvement step. Given a graph and a budget k, which k edges do we add to the graph to minimise its dilation? Gudmundsson and Wong [TALG'22] provided the first positive result for this problem, but their approximation factor is linear in k.
Our main result is a (2 √[r]{2} k^{1/r},2r)-bicriteria approximation that runs in O(n³ log n) time, for all r ≥ 1. In other words, if t^* is the minimum dilation after adding any k edges to a graph, then our algorithm adds O(k^{1+1/r}) edges to the graph to obtain a dilation of 2rt^*. Moreover, our analysis of the algorithm is tight under the Erdős girth conjecture.
@InProceedings{buchin_et_al:LIPIcs.ESA.2024.36,
author = {Buchin, Kevin and Buchin, Maike and Gudmundsson, Joachim and Wong, Sampson},
title = {{Bicriteria Approximation for Minimum Dilation Graph Augmentation}},
booktitle = {32nd Annual European Symposium on Algorithms (ESA 2024)},
pages = {36:1--36:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-338-6},
ISSN = {1868-8969},
year = {2024},
volume = {308},
editor = {Chan, Timothy and Fischer, Johannes and Iacono, John and Herman, Grzegorz},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2024.36},
URN = {urn:nbn:de:0030-drops-211079},
doi = {10.4230/LIPIcs.ESA.2024.36},
annote = {Keywords: Greedy spanner, Graph augmentation}
}