答案1
这只是一个aligned
(带有手动枚举)equation
和一个自定义的\tag
:
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\ldots the solutions
\begin{equation}
\begin{aligned}
& (i) & \limsup_{t \to \infty} \, \lvert y(t) \rvert &< \infty, \\
& (ii) & \liminf_{t \to \infty} \, \lvert y(t) \rvert &= 0 \Rightarrow
\lim_{t \to \infty} y(t) = 0.
\end{aligned}
\tag{$L$}
\end{equation}
\end{document}