Lecture Notes on Bayesian Estimation and Classification
《Lecture Notes on Bayesian Estimation and Classification》 · 第 43 页 · Section 1.6「Permutation Groups and Group Actions」，Exercises 1.6，题 14
Let $W=H\sim K$ be the standard wreath product of an abelian group $H\ne1$ and an arbitrary group $K$. Prove that the center of $W$ equals the set of elements in the base group all of whose component are equal. (This is called the diagonal subgroup of the base group.)