diff -r f345e89895f5 -r fba480bbc9f7 hws/hw04.tex
--- a/hws/hw04.tex	Mon Jun 29 21:05:34 2020 +0100
+++ b/hws/hw04.tex	Mon Jun 29 21:13:49 2020 +0100
@@ -10,6 +10,20 @@
 
 \begin{enumerate}
 
+\item Given the regular expressions
+
+\begin{center}
+\begin{tabular}{ll}    
+  1) & $(ab + a)\cdot (\ONE + b)$\\
+  2) & $(aa + a)^*$\\
+\end{tabular}
+\end{center}
+
+there are several values for how these regular expressions can
+recognise the strings (for 1) $ab$ and (for 2) $aaa$. Give in each case
+\emph{all} the values and indicate which one is the POSIX value.
+  
+
 \item If a regular expression $r$ does not contain any occurrence of $\ZERO$,  
 is it possible for $L(r)$ to be empty? Explain why, or give a proof.