\begin{frame}
  \frametitle{Introduction}
 
  \begin{minipage}{0.5\textwidth}
    \begin{center}
    \begin{tikzpicture}[
        default,
        point/.style={circle, draw=blue, thick, inner sep=3pt, minimum size=9mm},
        node distance=20mm]
  
      \node (3) [point] {};
      \node [lo=3] {$w_3$};
      
      \node (2) [point, below right of=3] {\alt<-2>{$\lab{q}$}{}};
      \node [aro=2] {$w_2$};

      \node (1) [point, below left of=3] {$\lab{q}$};
      \node [alo=1] {$w_1$};

      \begin{scope}[shorten <= 1mm, shorten >= 1mm, very thick,>=stealth]
        \draw [->] (1) to (3);
        \draw [->] (3) to (2);
        \draw [->] (3) to[out=45,in=45+90,looseness=4] (3);
      \end{scope}

      \draw [rounded corners=2mm, dashed] (-25mm,-20mm) rectangle (25mm,11mm);
      \node at (-25mm,8mm) [anchor=north east,inner sep=2mm] {$\mathcal{M}_{\alt<-2>{1}{2}}$};
    \end{tikzpicture}
    \end{center}
  \end{minipage}
  \begin{minipage}{0.49\textwidth}
    \begin{talign}
    \onslide<-2>{
      w_2 &\fc \all\some q \\
      w_3 &\fc q \to \all\some q \\
      w_2 &\fc q \\
      w_3 &\fc \some q \\
      w_1 &\fc \all\some q \\[1ex]
    }
      \M_1  & \models  q \to \all\some q \\
      \mpause[2]{ \M_2  & \not\models  q \to \all\some q }
    \end{talign}
  \end{minipage}
  \smallskip\pause
  
  \begin{alertblock}{Question}
    Can you change the labelling such that such that
    \begin{talign}
      \M \models q \to \all\some q
    \end{talign}
    is no longer valid?
  \end{alertblock}
  \pause\smallskip
  
  Yes, for example, by setting $\lab{L}(w_2) = \{\; \}$\;.
\end{frame}