\begin{frame}
   \frametitle{Validity in Frames}

  \begin{goal}{Validity in frames}
    A formula $\phi$ is \emph{valid in frame} $\F = (W,R)$, denoted
    \begin{talign}
      \F \models \phi\;,
    \end{talign}
    if \emph{for every labelling} $L$:
    \begin{center}
      the Kripke model $\M = (W,R,L)$ makes $\phi$ true \;\;($\M \models \phi$)
    \end{center}
  \end{goal}
  \hint{We say that $\M$ is a Kripke model on $\F$.}
  \pause

  \begin{exampleblock}{}
  \begin{minipage}{0.5\textwidth}
    \exampleSymmetric
  \end{minipage}
  \begin{minipage}{0.49\textwidth}
    \begin{talign}
      \mpause[1]{\F &\models q \to \all \some q} \\
      \mpause{\F &\mpause{\models} p \vee \neg p}  \\
      \mpause{\F &\mpause{\not\models} \some p \to \all p} \\
      \mpause{\F &\mpause{\models} \all p \to \some p}
    \end{talign}
  \end{minipage}
  \end{exampleblock}
\end{frame}