答案1
使用align
和aligned
环境:
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align*}
\left\{\begin{aligned}
\varphi(\sigma) & =1\\
\varphi(\tau) & =0
\end{aligned}\right.
\Rightarrow N=\langle \sigma^2,\tau\rangle
&&
\left\{\begin{aligned}
\varphi(\sigma) & =0\\
\varphi(\tau) & =1
\end{aligned}\right.
\Rightarrow N=\langle \sigma\rangle
&&
\left\{\begin{aligned}
\varphi(\sigma) & =1\\
\varphi(\tau) & =1
\end{aligned}\right.
\Rightarrow N=\langle \sigma^2,\tau\sigma\rangle
\end{align*}
\end{document}