The contact process on the complete graph with random vertex-dependent infection rates

Abstract

We study the contact process on the complete graph on n vertices where the rate at which the infection travels along the edge connecting vertices i and j is equal to λwiwjn for some λ>0, where wi are i.i.d. vertex weights. We show that when E[w12] 0 such that for λ λc the contact process lives for an exponential amount of time. Moreover, we give a formula for λc and when λ>λc we are able to give precise approximations for the probability that a given vertex is infected in the quasi-stationary distribution. Our results are consistent with a non-rigorous mean field analysis of the model. This is in contrast to some recent results for the contact process on power law random graphs where the mean field calculations suggested that λc>0 when in fact λc=0. © 2010 Elsevier B.V. All rights reserved.