Almost all graphs with average degree 4 are 3-colorable

  • Authors:
  • Dimitris Achlioptas;Cristopher Moore

  • Affiliations:
  • Microsoft Research;University of New Mexico

  • Venue:
  • STOC '02 Proceedings of the thiry-fourth annual ACM symposium on Theory of computing
  • Year:
  • 2002

Quantified Score

Hi-index 0.00

Visualization

Abstract

The technique of using differential equations to approximate the mean path of Markov chains has proved very useful in the average-case analysis of algorithms. Here, we significantly expand the range of this technique, by showing that it can be used to handle algorithms that favor high-degree vertices. In particular, we consider the problem of 3-coloring sparse random graphs and analyze a "smoothed" version of the Brelaz heuristic. This allows us to prove that i) almost all graphs with average degree d, i.e. G(n,p=d/n), are 3-colorable for d&xie; 4.03, and that ii) almost all 4-regular graphs are 3-colorable. This improves over the previous lower bound of 3.847 for the G(n,p) 3-colorability threshold and gives the first non trivial result on the 3-colorability of random regular graphs.