outer automorphism

《代数学引论》 · 第 72 页

自同构群对于内自同构群的商群 $\operatorname{Aut}(G)/\operatorname{In}(G)$ 称为群 $G$ 的外自同构群。

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《Lecture Notes on Bayesian Estimation and Classification》 · 第 26 页 · Section 1.5「Endomorphisms and Automorphisms」

An automorphism of $G$ which is not inner is called outer; the quotient group $\operatorname{Out}G=(\operatorname{Aut}G)/(\operatorname{Inn}G)$ is called the outer automorphism group of $G$.