\begin{frame}
  \small
  
  \begin{theorem}%[Rusinowitch 1987, Middeldorp 1989]
  \smallskip
  The disjoint union of terminating TRSs $\RR$ and $\SS$ is terminating if:
  \begin{itemize}
  \item
  $\RR$ and $\SS$ lack collapsing rules, or
  \item
  $\RR$ and $\SS$ lack duplicating rules, or
  \item
  $\RR$ or $\SS$ lacks both collapsing and duplicating rules.
  \smallskip
  \end{itemize}
  \end{theorem}
  
  \bigskip
  
  \begin{corollary}<2->
  \smallskip
  Termination is preserved under signature extension.
  \smallskip
  \end{corollary}
\end{frame}