\begin{frame}{Exercise} \begin{exampleblock}{} Construct a Turing machine accepting all words of \emph{odd} length over the alphabet $\Sigma = \{a,b\}$. \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[bend left=20] node [label,above,align=center] {$a/a$ $R$\\$b/b$ $R$} (q1); \draw (q1) to[bend left=20] node [label,below,align=center] {$a/a$ $R$\\$b/b$ $R$} (q0); \draw (q1) to node [label,above] {$\Box/\Box$ $R$} (q2); \end{tikzpicture} \vspace{-1ex} \end{center} Multiple labels on an arrow are short for multiple transitions. \end{exampleblock} \end{frame}