Improved Distributed Delta-Coloring
Mohsen Ghaffari, Juho Hirvonen, Fabian Kühn, Yannic Maus · Distributed Computing · 2018
Abstract We present a randomized distributed algorithm that computes a $$\Delta $$ Δ -coloring in any non-complete graph with maximum degree $$\Delta \ge 4$$ Δ ≥ 4 in $$O(\log \Delta ) + 2^{O(\sqrt{\log \log n})}$$ O ( log Δ ) + 2 O ( log log n ) rounds, as well as a randomized algorithm that computes a $$\Delta $$ Δ -coloring in $$O((\log \log n)^2)$$ O ( ( log log n ) 2 ) rounds when $$\Delta \in [3, O(1)]$$ Δ ∈ [ 3 , O ( 1 ) ] . Both these algorithms improve on an $$O(\log ^3 n / \log \Delta )$$ O ( log 3 n / log Δ ) -round algorithm of Panconesi and Srinivasan (STOC’93), which has remained the state of the art for the past 25 years. Moreover, the latter algorithm gets (exponentially) closer to an $$\Omega (\log \log n)$$ Ω ( log log n ) round lower bound of Brandt et al. (STOC’16).