--- a/hws/hw06.tex	Fri Oct 28 09:08:13 2022 +0100
+++ b/hws/hw06.tex	Fri Nov 04 12:07:40 2022 +0000
@@ -68,8 +68,20 @@
       advantages to first lex a string and then feed a
       sequence of tokens as input to the parser?
 
+\item The injection function for sequence regular expressions is defined
+      by three clauses:
 
-  
+\begin{center}
+\begin{tabular}{l@{\hspace{1mm}}c@{\hspace{1mm}}l}
+  $\inj\,(r_1 \cdot r_2)\,c\,\,Seq(v_1,v_2)$ & $\dn$  & $Seq(\inj\,r_1\,c\,v_1,v_2)$\\
+  $\inj\,(r_1 \cdot r_2)\,c\,\,\Left(Seq(v_1,v_2))$ & $\dn$  & $Seq(\inj\,r_1\,c\,v_1,v_2)$\\
+  $\inj\,(r_1 \cdot r_2)\,c\,\,Right(v)$ & $\dn$  & $Seq(\textit{mkeps}(r_1),\inj\,r_2\,c\,v)$\\
+\end{tabular}
+\end{center}
+
+Explain why there are three cases in the injection function for sequence
+regular expressions. 
+      
 \item \POSTSCRIPT        
 \end{enumerate}