Centred quadratic stochastic operators

Abstract

We study the weak convergence of iterates of so-called centred kernel quadratic stochastic operators. These iterations, in a population evolution setting, describe the additive perturbation of the arithmetic mean of the traits of an individual's parents and correspond to certain weighted sums of independent random variables. We show that one can obtain weak convergence results under rather mild assumptions on the kernel. Essentially it is sufficient for the distribution of the perturbing random variable to have a finite variance or have tails controlled by a power function. The advantage of these conditions is that in many cases they are easily verifiable by an applied user. Additionally, the representation by sums of random variables implies an efficient simulation algorithm to obtain random variables approximately following the law of the iterates of the quadratic stochastic operator, with full control of the degree of approximation. Our results also indicate where lies an intrinsic difficulty in the analysis of the behaviour of quadratic stochastic operators.