235   $r^*$ & $\mapsto$ &  \texttt{STAR(r)} & \texttt{r.\%}

   235   $r^*$ & $\mapsto$ &  \texttt{STAR(r)} & \texttt{r.\%}

   236 \end{tabular}    

   236 \end{tabular}    

   237 \end{center}  

   237 \end{center}  

   238 

   238 

   239 \noindent

   239 \noindent

   241 binary (+ / \texttt{ALT}) and the other is n-ary ($\sum$ /

   241 binary (+ / \texttt{ALT}) and the other is n-ary ($\sum$ /

   242 \texttt{ALTs}). The latter takes a list of regular expressions as

   242 \texttt{ALTs}). The latter takes a list of regular expressions as

   243 argument.  In what follows we shall use $rs$ to stand for lists of

   243 argument.  In what follows we shall use $rs$ to stand for lists of

   244 regular expressions. When the list is empty, we shall write $\sum\,[]$;

   244 regular expressions. When the list is empty, we shall write $\sum\,[]$;

   245 if it is non-empty, we sometimes write $\sum\,[r_1,..., r_n]$.

   245 if it is non-empty, we sometimes write $\sum\,[r_1,..., r_n]$.