= Wright–Fisher binomial sampling chain
{c}
{title2=$Z_{k+1}\mid Z_k=j\sim\operatorname{Bin}(n,j/n)$}
An urn with $j$ red balls among $n$ is sampled independently $n$ times with replacement, and the next generation's red count is the number of red draws. Its proportion is a bounded discrete-time <martingale>. Accelerating generation time by $n$ gives a <Wright–Fisher diffusion> limit: the one-step variance of the proportion is $x(1-x)/n$, and the higher moments make Taylor remainders negligible.
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