Class Field Theory
《Class Field Theory》 · 第 81 页 · Chapter 4，Section 4.1「Representations」
The inclusion map of $G$ into $\mathrm{GL}(n;\mathbb C)$ (i.e., the map $\Pi(A) = A$) is a representation of $G$, called the standard representation of $G$. If $G$ happens to be contained in $\mathrm{GL}(n;\mathbb R) \subset \mathrm{GL}(n;\mathbb C)$, then we can also think of the standard representation as a real representation.