答案1
这可以通过不同的方法来实现,我在这里提出一个如何实现的想法。
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\documentclass[aspectratio=169]{beamer}
\usetheme{Madrid} \usecolortheme{fly}
\setbeamercolor{normal text}{fg=white}
\setbeamercolor{frametitle}{fg=red!40}
\setbeamertemplate{navigation symbols}{} % Remove nav. icons
\usepackage{graphicx}
\usebackgroundtemplate
{\includegraphics[width=\paperwidth,height=\paperheight]{background-board.png}}
\usepackage{ulem,xcolor}
\makeatletter
\newcommand{\coloruuline}[2]{%
\UL@protected\def\temp@uuline{\leavevmode \bgroup
\UL@setULdepth
\ifx\UL@on\UL@onin \advance\ULdepth2.8\p@\fi
\markoverwith{\textcolor{#1}{\lower\ULdepth\hbox
{\kern-.03em\vbox{\hrule width.2em\kern1\p@\hrule}\kern-.03em}}}%
\ULon}%
\temp@uuline{#2}%
}
\makeatother
\newcommand{\rul}[1]{\coloruuline{red!40}{#1}}
\title[Example]{Beamer example}
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\begin{document}
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\section{First section}
\begin{frame}[plain]{The ergotic theorem}
\rul{Theorem} (Von Neumann's Ergodic Theorem)
Let $(X, \mathcal{X}, \mu, T)$ be a measure preserving system and $f \in L^{2}(\mu)$. Then
\begin{equation*}
\lim _{n \rightarrow \infty} \frac{1}{n} \sum_{i=0}^{n-1} f \circ T^{i} \rightarrow \mathbb{E}(f \mid \mathcal{I}(T))
\end{equation*}
\vspace{10pt}
\rul{Theorem} (Weak version)
Let $(X, \mathcal{X}, \mu, T)$ be a measure preserving system and $A \in \mathcal{X}, \mu(A)>0 .$ Then
\begin{equation*}
\lim _{n \rightarrow \infty} \mu\left(A \cap T^{-n} A\right) \geq \mu(A)^{2}
\end{equation*}
\end{frame}
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\end{document}
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% EOF
答案2
这个怎么样?我为此创建了一个新环境。我认为一切都应该以内联方式描述。
\documentclass{beamer}
\usetheme{default}
\def\myEmphColor{red}% <== ADAPT COLOR HERE.
\usepackage{amsmath,ulem,ifthen}
\setbeamercolor{frametitle}{fg=\myEmphColor}
\usebackgroundtemplate{\includegraphics[width=\paperwidth,height=\paperheight]{example-image-duck}}% Simply use a blackboard-image of correct size here. Sorry for stretching you, Mr. Duck!
\newenvironment{mythm}[1][]{% create new environment with 1 optional parameter.
\setbeamercolor{block title}{fg=black}%
\setbeamercolor{block body}{fg=black}%
\begin{block}{{%
\color{\myEmphColor}\uuline{\color{black}Theorem}}% print 'Theorem' and underline it twice in color 'myEmphColor'.
\ifthenelse{\equal{#1}{}}{}{ (#1)}}% if given, add the optional theorem name in parentheses.
}{%
\end{block}%
}
\begin{document}
\begin{frame}{The ergodic theorem}
\begin{mythm}[Von Neumann's Ergodic Theorem]
Let $(X,\mathcal X,\mu,T)$ be a measure preserving system and $f\in L^2(\mu)$. Then
\begin{equation*}
\lim_{n\to\infty}\frac{1}{n}\sum_{i=0}^{n-1}f\circ T^i\to\mathbb E(f\vert\mathcal I(T)).
\end{equation*}
\end{mythm}
\begin{mythm}% <- works without theorem title, too.
Let $(X,\mathcal X,\mu,T)$ be a measure preserving system and $A\in\mathcal X$, $\mu(A)>0$. Then
\begin{equation*}
\lim_{n\to\infty}\mu(A\cap T^{-n}A)\geq\mu(A)^2.
\end{equation*}
\end{mythm}
\end{frame}
\end{document}