\begin{frame}[t]
  \frametitle{Cardinality Limits: Alternative Notations}

  \begin{alertblock}{}
    There are many different notations for ER models.
  \end{alertblock}
  \bigskip
  
  For example: Bachman style
  \begin{center}
    \includegraphics[width=.6\textwidth]{images/notation3.png}
  \end{center}
\end{frame}