We consider the problem of maintaining a proper (Δ + 1)-vertex coloring in a graph on n-vertices and maximum degree Δ undergoing edge insertions and deletions. We give a randomized algorithm with amortized update time Õ(n^{2/3}) against adaptive adversaries, meaning that updates may depend on past decisions by the algorithm. This improves on the very recent Õ(n^{8/9})-update-time algorithm by Behnezhad, Rajaraman, and Wasim (SODA 2025) and matches a natural barrier for dynamic (Δ+1)-coloring algorithms. The main improvements are on the densest regions of the graph, where we use structural hints from the study of distributed graph algorithms.
@InProceedings{flin_et_al:LIPIcs.ICALP.2025.79, author = {Flin, Maxime and Halld\'{o}rsson, Magn\'{u}s M.}, title = {{Faster Dynamic (\Delta+1)-Coloring Against Adaptive Adversaries}}, booktitle = {52nd International Colloquium on Automata, Languages, and Programming (ICALP 2025)}, pages = {79:1--79:21}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-372-0}, ISSN = {1868-8969}, year = {2025}, volume = {334}, editor = {Censor-Hillel, Keren and Grandoni, Fabrizio and Ouaknine, Jo\"{e}l and Puppis, Gabriele}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2025.79}, URN = {urn:nbn:de:0030-drops-234560}, doi = {10.4230/LIPIcs.ICALP.2025.79}, annote = {Keywords: Dynamic Graph Algorithms, Coloring} }
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