\begin{frame}{Exercise} \begin{exampleblock}{} Given is the following NFA: \begin{center} \vspace{-.5ex} \input{tikz/nfa1.tex} \vspace{-1.5ex} \end{center} \emph{Construct an NFA that accepts the reverse language:} \pause \begin{center} \vspace{-.5ex} \begin{tikzpicture}[default,node distance=20mm,->] \node (q0) [fstate] {$q_0$}; \node (q1) [state,right of=q0] {$q_1$}; \draw ($(q1) + (-7mm,7mm)$) -- (q1); \node (q2) [fstate,right of=q1] {$q_2$}; \draw [<-] (q0) to[bend left=10] node [label,above] {$a$} (q1); \draw [<-] (q0) to[bend left=-10] node [label,below] {$\lambda$} (q1); \draw [<-] (q1) to[bend left=0] node [label,above] {$b$} (q2); \draw (q1) to[out=40,in=100,looseness=5] node [label,above right] {$b$} (q1); \draw [<-] (q2) to[out=-130,in=-50,looseness=0.5] node [label,below] {$a$} (q0); \end{tikzpicture} \end{center} \end{exampleblock} \end{frame}