Hostname: page-component-cd9895bd7-hc48f Total loading time: 0 Render date: 2024-12-27T21:56:07.587Z Has data issue: false hasContentIssue false

Choice Numbers of Graphs: a Probabilistic Approach

Published online by Cambridge University Press:  12 September 2008

Noga Alon
Affiliation:
Department of Mathematics, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel and Bellcore, Morristown, NJ 07960, USA

Abstract

The choice number of a graph G is the minimum integer k such that for every assignment of a set S(v) of k colors to every vertex v of G, there is a proper coloring of G that assigns to each vertex v a color from S(v). By applying probabilistic methods, it is shown that there are two positive constants c1 and c2 such that for all m ≥ 2 and r ≥ 2 the choice number of the complete r-partite graph with m vertices in each vertex class is between c1r log m and c2r log m. This supplies the solutions of two problems of Erdős, Rubin and Taylor, as it implies that the choice number of almost all the graphs on n vertices is o(n) and that there is an n vertex graph G such that the sum of the choice number of G with that of its complement is at most O(n1/2(log n)1/2).

Type
Research Article
Copyright
Copyright © Cambridge University Press 1992

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

[1]Alon, N. (1992) The strong chromatic number of a graph, Random Structures and Algorithms 3 17.CrossRefGoogle Scholar
[2]Alon, N. and Spencer, J. H. (1991) The Probabilistic Method, Wiley.Google Scholar
[3]Alon, N. and Tarsi, M. (in press) Colorings and orientations of graphs, Combinatorica.CrossRefGoogle Scholar
[4]Bollobás, B. (1988) The chromatic number of random graphs, Combinatorica 8 4955.CrossRefGoogle Scholar
[5]Bollobás, B. (1985) Random Graphs, Academic Press.Google Scholar
[6]Chetwynd, A. and Häggkvist, R. (1989) A note on list colorings, J. Graph Theory 13 8795.CrossRefGoogle Scholar
[7]Erdős, P., Rubin, A. L. and Taylor, H. (1979) Choosability in graphs, Proc. West Coast Conf. on Combinatorics, Graph Theory and Computing, Congressus Numerantium XXVI 125157.Google Scholar
[8]Vizing, V. G. (1976) Coloring the vertices of a graph in prescribed colors (in Russian), Diskret. Analiz. No. 29, Metody Diskret. Anal. v. Teorii Kodov i Shem 101 310.Google Scholar