Conjugation action on itself

A group acts on itself by conjugation g·x = gxg^{-1}
Conjugation action on itself

Proposition (Conjugation action). Let GG be a . Define a map G×GGG\times G\to G by

gx:=gxg1. g\cdot x := gxg^{-1}.

Then this defines a of GG on itself, called the .

Context. The orbits of this action are the in GG, and stabilizers are centralizers. This action is the mechanism behind the class equation and many counting arguments.