\documentclass{beamer}
\usetheme{moloch}   % new metropolis
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\setmainfont[
    ItalicFont={Fira Sans Italic},
    BoldFont={Fira Sans Medium},
    BoldItalicFont={Fira Sans Medium Italic}
]{Fira Sans}
\setsansfont[
    ItalicFont={Fira Sans Italic},
    BoldFont={Fira Sans Medium},
    BoldItalicFont={Fira Sans Medium Italic}
]{Fira Sans}
\setmonofont[BoldFont={Fira Mono Medium}]{Fira Mono}
\AtBeginEnvironment{tabular}{%
    \addfontfeature{Numbers={Monospaced}}
}
\usepackage{firamath-otf}

\title{Connectivity Interdiction \& \\ Perturbed Graphic Matroid Cogirth}
\date{\today}
\author{Cong Yu}
\institute{A\&L Group, UESTC}
\begin{document}
\maketitle
\section{Connectivity interdiction}
\begin{frame}{Connectivity interdiction}
\begin{problem}[CI]

\end{problem}
\begin{theorem}[aaa]
sdfsdf
\end{theorem}
\begin{lemma}[aaa]
sdfsdf
\end{lemma}
\begin{proof}
	sdfs
\end{proof}

\end{frame}
\section{Computing cogirth in perturbed graphic matroids}
\begin{frame}{Perturbed graphic matroids}
\end{frame}
\end{document}