905 design task. Having these regular expressions at our disposal, we can

   905 design task. Having these regular expressions at our disposal, we can

   906 form the regular expression

   906 form the regular expression

   907 

   907 

   908 \begin{figure}[t]

   908 \begin{figure}[t]

   909 \begin{center}

   909 \begin{center}

   911 \end{center}

   911 \end{center}

   912 \caption{The Fibonacci program in the While-language.\label{while}}

   912 \caption{The Fibonacci program in the While-language.\label{while}}

   913 \end{figure}

   913 \end{figure}

   914 

   914 

   915 \begin{center}

   915 \begin{center}