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\begin{frame}
  \frametitle{Symmetric Frames: $q \to \all\some q$}

  We can now make precise why it is impossible to make 
  \begin{align*}
    q \to \all\some q
  \end{align*}
  false on the frame $\F$.
  \medskip
    
  \begin{center}
    \exampleSymmetric
  \end{center}
  \pause

  \begin{alertblock}{}
  The reason is that $R$ is \emph{symmetric}:
  $\myall{x}{\myall{y}{\big(R(x,y) \to R(y,x)\big)}}$
  \end{alertblock}
\end{frame}