A 1.43-competitive online graph edge coloring algorithm in the random order arrival model

  • Authors:
  • Bahman Bahmani;Aranyak Mehta;Rajeev Motwani

  • Affiliations:
  • Stanford University;Google, Inc., Mountain View, CA;Stanford University

  • Venue:
  • SODA '10 Proceedings of the twenty-first annual ACM-SIAM symposium on Discrete Algorithms
  • Year:
  • 2010

Quantified Score

Hi-index 0.00

Visualization

Abstract

A classic theorem by Vizing proves that if the maximum degree of a graph is Δ then it is possible to color its edges, in polynomial time, using at most Δ+1 colors. However, this algorithm is offline, i.e., it assumes the whole graph is known in advance. A natural question then is how well we can do in the online setting, where the edges of the graph are revealed one by one, and we need to color each edge as soon as it is added to the graph. Online edge coloring has an important application in fast switch scheduling. Here, a natural model is that edges arrive online, but in a random permutation. Even in the random permutations model, the best analysis for any algorithm is factor 2, which comes from the simple greedy algorithm (which is factor 2 even in the worst case online model). The algorithm of Aggarwal et al. [1] provides a 1+o(1) factor algorithm, but for the case of multigraphs, when Δ = ω(n2), where n is the number of vertices. In this paper, we show that for graphs with Δ = ω(log n), it is possible to color the graph with 1.43Delta; + o(Δ) colors in the online random order model. Our algorithm is inspired by a 1.6 factor distributed offline algorithm of Panconesi and Srinivasan [9], which we extend by reusing colors online in multiple rounds.