重新学习 Material For Mkdocs

开始在 GitHub 上记录学习过程.

一切都有迹可循。

\[ \operatorname{ker} f=\{g\in G:f(g)=e_{H}\}{\mbox{.}} \]

The homomorphism \(f\) is injective if and only if its kernel is only the singleton set \(e_G\), because otherwise \(\exists a,b\in G\) with \(a\neq b\) such that \(f(a)=f(b)\).