\begin{frame} \frametitle{Example} \begin{exampleblock}{} Prove \quad$p \vee \neg q,\; \neg p \to q \;\vdash\; p$\quad! \medskip \begin{tikzpicture} \naturaldeduction{ \mpause[1]{ \proofstep{$p \vee \neg q$}{premise}; } \mpause{ \proofstep{$\neg p \to q$}{premise}; } \mpause{ \proofbox{ \mpause{ \proofstep{$p$}{assumption}; } } } \mpause{ \proofbox{ \mpause{ \proofstep{$\neg q$}{assumption}; } \mpause{ \proofstep{$\neg\neg p$}{MT 2,4}; } \mpause{ \proofstep{$p$}{$\neg\neg_e$ 5}; } } } \mpause{ \proofstep{$p$}{$\vee_e$ 1,\;3--3,\;4--6}; } } \end{tikzpicture} \end{exampleblock} \end{frame}