An Optimal Decentralized (Δ+ 1)-Coloring Algorithm

02/12/2020

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by   Daniel Bertschinger, et al.

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Consider the following simple coloring algorithm for a graph on n vertices. Each vertex chooses a color from {1, , Δ(G) + 1} uniformly at random. While there exists a conflicted vertex choose one such vertex uniformly at random and recolor it with a randomly chosen color. This algorithm was introduced by Bhartia et al. [MOBIHOC'16] for channel selection in WIFI-networks. We show that this algorithm always converges to a proper coloring in expected O(n logΔ) steps, which is optimal and proves a conjecture of Chakrabarty and Supinski [SOSA'20].