\documentclass{beamer}
\input{prolog}
%Information to be included in the title page:
\title{Typinferenz für Java mit Wildcards}
\author{Andreas Stadelmeier}
\institute{DHBW Stuttgart Campus Horb}
\date{2024}

\begin{document}

\frame{\titlepage}

\newcommand{\rulenameAfter}[1]{\begin{array}[b]{l}\rulename{#1}\\[-0.5em] \ \end{array}}

\begin{frame}[fragile]
\frametitle{Motivation}
$
\begin{array}[b]{c}
\begin{array}[b]{c}
\texttt{emptyList()} : \exptype{List}{\exptype{List}{\type{String}}}
\\
\hline
\texttt{emptyList().get()} : \exptype{List}{\type{String}}
\end{array} \rulenameAfter{T-Call}
\\
\hline
\texttt{emptyList().get().get()} : \type{String}
\end{array} \rulenameAfter{T-Call}
$
\end{frame}

\end{document}
