A tantalizing open question in the theory of distributed computing asks whether a graph with maximum degree Δ can be colored with Δ + 1 colors in polylog deterministic steps in the distributed model of computation. Linial introduced the notion of a t-neighborhood graph of a given graph G and showed that the chromatic number of this graph is a lower bound on the number of colors that G can be colored with in t steps of the distributed model. In this paper we show that the chromatic number of any t-neighborhood graph is at most Δ + 1 for some t = O(log3 n). This implies that current techniques for proving lower bounds on the distributed complexity of Δ + 1-coloring are not strong enough to give a negative answer to the above open problem. The proof of this result is based on the analysis of a randomized algorithm for this problem using martingale inequalities. We also show that in a nonconstructive sense the Δ+ 1-coloring problem can be solved in polylog time for an infinite class of graphs including vertex-transitive graphs.
CITATION STYLE
Kelsen, P. (1996). Neighborhood graphs and distributed Δ + 1-coloring. In Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) (Vol. 1097, pp. 223–233). Springer Verlag. https://doi.org/10.1007/3-540-61422-2_134
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