inner automorphism

An **inner automorphism** $\phi:G\to G$ of a group $G$ is any automorphism $\phi_g$ of the form $h\mapsto g h g^{-1}$. The inner automorphisms form a subgroup $Inn(G)$, called the **inner automorphism group** of $G$, of the entire automorphism group $Aut(G)$; it is the image of the natural map $G\to Aut(G)$ given by $g\mapsto\phi_g$. The center of a group $G$ is precisely the kernel of this natural map. Similarly, the monoidal center due to Drinfel’d and Majid, in the case when the monoidal category is Picard, is a $2$-category-theoretic kernel (an observation due to L. Breen).

Higher analogues of the inner automorphism group were studied by Roberts and Schreiber.

Last revised on September 9, 2009 at 00:25:19. See the history of this page for a list of all contributions to it.