Every group can be partitioned into equivalence classes called conjugacy classes. 所有群都可以划分成叫做共轭类的等价类。
And if we apply the same property to the identity automorphism, we get the closedness theorem for conjugacy classes of finite order in Lie groups. 而把同样的性质应用到恒同自同构，我们会得到李群中有限阶共轭类的闭性定理。
