我有一个非常困难的要求，我在下面详细解释了它（参考屏幕截图），标签如下：
\documentclass[10pt]{book}
\usepackage{mathtools}%to load amsmath
\begin{document}
\makeatletter
\newbox\eqnskipbox%
\newdimen\eqnskipdimen%
\setbox\eqnskipbox=\hbox{\bgroup$\displaystyle\dfrac{\int}{\int}\displaystyle\sum^{i=1}_{j=1}$\vphantom{$\displaystyle\dfrac{\int}{\int}$}\vphantom{$\displaystyle\sum^{i=1}_{j=1}$}\vphantom{hy}\egroup}%
\eqnskipdimen=\ht\eqnskipbox%
\renewcommand\normalsize{%
\@setfontsize\normalsize{10}{13}%
\advance\eqnskipdimen by -11\p@%
\abovedisplayskip \eqnskipdimen%
\abovedisplayshortskip \z@ %\@plus3\p@%
\belowdisplayshortskip 3.5\p@ %\@plus3\p@ \@minus3\p@%
\belowdisplayskip \eqnskipdimen%
\let\@listi\@listI}%
\normalsize
\let\@bls\baselineskip
\makeatother
In business, planning is a process that helps a firm determine text
for dummy a course of action in order to achieve future objectives, given limited resources.
\[
a+b=c
\]
This is for testing
\begin{align}
\frac{a}{b}\frac{\int}{\int}
\end{align}
A typical financial planning process begins with evaluating the market environment and past performance in order to identify business strategic and operating priorities.
\begin{equation}
\sum^{i=1}_{j=1}
\end{equation}
Next we define expectations. Given an initial state $s_{0}$, a feasible
plan $\pi $ from $s_{0},$ and the stochastic kernels $P_{t},$ $t=1,\ldots,T,$
define a probability measure on $\mathcal{S}^{t}$ as dummy text
\begin{align}
\mu ^{t}\left( s_{0},B;\pi \right) =&\int_{B_{1}}\ldots
\int_{B_{t-1}}\int_{B_{t}}P_{t}\left( s_{t-1},\pi _{t-1}\left(
s^{t-1}\right)\! ;\ ds_{t}\right) \notag\\
&\times P_{t-1}\left( s_{t-2},\pi _{t-2}\left( s^{t-2}\right)
;\ ds_{t-1}\right) \cdots\ P_{1}\left( s_{0},\pi _{0};\ ds_{1}\right)\!, \label{mu0t}
\end{align}
for any $B=B_{1}\times \cdots\times $ $B_{t}\in \mathcal{S}^{t}$, where we set $\pi_{0}({s^{0})}=\pi_{0}$ and $s^{0}=s_0$ by convention.
\end{document}
我需要修复所有出现above/below的空间，display math例如20pt base to base简单的数学、分数、求和符号等。请参阅以下屏幕截图以获取更多说明：
期待您的所有宝贵建议...
有人能建议如何实现这个吗？请...