,
Ian DeHaan
,
Eun Jung Kim
,
Euiwoong Lee
Creative Commons Attribution 4.0 International license
We present a polynomial-time (α_{GW} + ε)-approximation algorithm for the Maximum Cut problem on interval graphs and split graphs, where α_{GW} ≈ 0.878 is the approximation guarantee of the Goemans-Williamson algorithm and ε > 10^{-34} is a fixed constant. To attain this, we give an improved analysis of a slight modification of the Goemans-Williamson algorithm for graphs in which triangles can be packed into a constant fraction of their edges. We then pair this analysis with structural results showing that both interval graphs and split graphs either have such a triangle packing or have maximum cut close to their number of edges. We also show that, subject to the Small Set Expansion Hypothesis, there exists a constant c > 0 such that there is no polyomial-time (1 - c)-approximation for Maximum Cut on split graphs.
@InProceedings{ahn_et_al:LIPIcs.APPROX/RANDOM.2025.20,
author = {Ahn, Jungho and DeHaan, Ian and Kim, Eun Jung and Lee, Euiwoong},
title = {{Approximating Maximum Cut on Interval Graphs and Split Graphs Beyond Goemans-Williamson}},
booktitle = {Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2025)},
pages = {20:1--20:22},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-397-3},
ISSN = {1868-8969},
year = {2025},
volume = {353},
editor = {Ene, Alina and Chattopadhyay, Eshan},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.APPROX/RANDOM.2025.20},
URN = {urn:nbn:de:0030-drops-243869},
doi = {10.4230/LIPIcs.APPROX/RANDOM.2025.20},
annote = {Keywords: Maximum cut, graph theory, interval graphs, split graphs}
}