考虑以下 MWE：
\documentclass{minimal}
\usepackage{amsmath}
\usepackage{graphics}
\newcommand*{\scaleandcenter}[2]{{\vcenter{\hbox{\scalebox{#1}{$#2$}}}}}
\newcommand*{\scalebig}[1]{\scaleandcenter{1.5}{#1}}
\newcommand*{\imp}{\mathop{\Rightarrow}}
\newcommand*{\Imp}{\mathbin{\scalebig{\imp}}}
\newcommand*{\blankrel}[1]{\mathrel{\phantom{#1}}}
\newcommand*{\Blank}{\blankrel{\Imp}}
\newcommand*{\Eq}{\mathrel{\scalebig{=}}}
\newcommand*{\apf}{\mathrel{\triangleleft}}
\newcommand*{\sgn}{\texttt{sgn}}
\begin{document}
We can expect $n!$ injective functions from $[n]$ to $[n]$. Therefore, we will have 6 terms in the summation above, corresponding to each of the 6 permutations in $S_n$:
\begin{align*}
&\Blank \pi_1 = e, \sgn(\pi_2) = 1\\
&\Imp \sgn(\pi_1) \prod_{j=1}^3 v_{\pi_1 \apf j, j} \\
&\Eq \prod_{j=1}^3 v_{\pi_1 \apf j, j} \\
&\Eq v_{1,1}v_{2,2}v_{3,3}
\end{align*}
\begin{align*}
&\Blank \pi_2 = \left(\begin{matrix}1 & 2\end{matrix}\right), \sgn(\pi_2) = -1\\
&\Imp \sgn(\pi_2) \prod_{j=1}^3 v_{\pi_2 \apf j, j} \\
&\Eq -\prod_{j=1}^3 v_{\pi_2 \apf j, j} \\
&\Eq -v_{2,1}v_{1,2}v_{3,3}
\end{align*}
\end{document}
它产生以下输出：
但是，请注意，第一个块与第二个块不对齐（\pi_1不对齐\pi_2）；这是为什么？如果在第二个块后添加更多对齐块，它们会对齐，只是第一个块略微“缩进”了？