Lecture Notes on Bayesian Estimation and Classification
《Lecture Notes on Bayesian Estimation and Classification》 · 第 31 页 · Section 1.6「Permutation Groups and Group Actions」
If $X$ is a nonempty set, a subgroup $G$ of the symmetric group $\operatorname{Sym}X$ is called a permutation group on $X$. […] The permutation group $G$ is said to be semiregular if $\operatorname{St}_G(x)=1$ for all $x$ in $X$. A regular permutation group is one that is both transitive and semiregular.