The jump of the clique chromatic number of random graphs

Abstract

The clique chromatic number of a graph is the smallest number of colors in a vertex coloring so that no maximal clique is monochromatic. In 2016 together with McDiarmid and Pralat we noted that around pm n^{-1/2} the clique chromatic number of the random graph G(n,p) changes by n^{\Omega(1)} when we increase the edge-probability p by n^{o(1)}, but left the details of this surprising phenomenon as an open problem. In this paper we settle this problem, i.e., resolve the nature of this polynomial jump of the clique chromatic number of the random graph G(n,p) around edge-probability p = n^{-1/2}. Our proof uses a mix of approximation and concentration arguments, which enables us (i) to go beyond Jansons inequality used in previous work and (ii) to determine the clique chromatic number of G(n,p) up to logarithmic factors for any edge-probability p. Joint work with Lyuben Lichev and Lutz Warnke.

Date
Oct 8, 2021 4:00 PM