,
Łukasz Kowalik
Creative Commons Attribution 4.0 International license
In 1965, Vizing [Vadim G. Vizing, 1965] showed that every planar graph of maximum degree Δ ≥ 8 can be edge-colored using Δ colors. The direct implementation of Vizing’s proof gives an algorithm that finds the coloring in O(n²) time for an n-vertex input graph. Chrobak and Nishizeki [Marek Chrobak and Takao Nishizeki, 1990] have shown a more careful algorithm, which improves the time to O(nlog n), though only for Δ ≥ 9. In this paper, we extend their ideas to get an algorithm also for the missing case Δ = 8. To this end, we modify the original recoloring procedure of Vizing. This generalizes to bounded genus graphs of maximum degree 8 in the sense that in time O(nlog n) the algorithm colors the graph using the optimal number of colors which may be 9 for relatively small graphs.
@InProceedings{jedrzejczak_et_al:LIPIcs.WG.2026.27,
author = {J\k{e}drzejczak, Patryk and Kowalik, {\L}ukasz},
title = {{The Planar Edge-Coloring Theorem of Vizing in O(nlog n) Time}},
booktitle = {52nd International Workshop on Graph-Theoretic Concepts in Computer Science (WG 2026)},
pages = {27:1--27:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-430-7},
ISSN = {1868-8969},
year = {2026},
volume = {376},
editor = {Goedgebeur, Jan and Rz\k{a}\.{z}ewski, Pawe{\l}},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.WG.2026.27},
URN = {urn:nbn:de:0030-drops-261931},
doi = {10.4230/LIPIcs.WG.2026.27},
annote = {Keywords: edge coloring, algorithm, planar, graph, Vizing, quasilinear}
}