\begin{frame}{Exercises (1)}

  \begin{exampleblock}{}
    Draw an NPDA $M$ with \alert{$L(M) = \{\,a^nb^{2n} \mid n\geq 0\,\}$}.
    \pause
    \begin{center}
      \begin{tikzpicture}[default,node distance=25mm,->,s/.style={minimum size=5mm}]
        \node (q0) [state,s] {$q_0$}; \draw ($(q0) + (-8mm,0mm)$) -- (q0); 
        \node (q1) [state,s,right of=q0] {$q_1$};
        \node (q2) [fstate,s,right of=q1] {$q_2$};
      
        \draw (q0) to node [label,above] {$b[1/\lambda]$} (q1);
        \draw (q1) to node [label,above] {$\lambda[0/\lambda]$} (q2);
        \draw (q0) to[bend right=20] node [label,below] {$\lambda[0/\lambda]$} (q2);
        \draw (q0) to[tloop] node [label,above] {$a[0/\alert{1}10]$} (q0);
        \draw (q0) to[bloop] node [label,below] {$a[1/\alert{1}11]$} (q0);
        \draw (q1) to[tloop] node [label,above] {$b[1/\lambda]$} (q1);
      \end{tikzpicture}
    \end{center}
  \end{exampleblock}
\end{frame}