\begin{frame}
  \frametitle{Derivation with Natural Deduction}
  
  \begin{exampleblock}{Derivation with Natural Deduction}
  Can we derive \quad$q \wedge \neg r$\quad from \quad$(p \wedge q) \wedge \neg r$\quad? 
  \pause\bigskip
  
  \begin{tikzpicture}
  \naturaldeduction{
    \proofstep{$(p \wedge q) \wedge \neg r$}{premise};   
    \mpause[1]{
    \proofstep{$p \wedge q$}{$\wedge_{e_1}$ 1};
    }
    \mpause{
    \proofstep{$q$}{$\wedge_{e_2}$ 2};
    }
    \mpause{
    \proofstep{$\neg r$}{$\wedge_{e_2}$ 1};
    }
    \mpause{
    \proofstep{$q \wedge \neg r$}{$\wedge_{i}$ 3, 4};
    }
  }
  \end{tikzpicture}
  \pause\pause\pause\pause\pause
  \bigskip
  
  Hence we have derived
  \begin{talign}
    (p \wedge q) \wedge \neg r \quad\vdash\quad q \wedge \neg r
  \end{talign}
  \end{exampleblock}
\end{frame}