--- a/hws/hw06.tex	Thu Oct 03 11:12:00 2019 +0100
+++ b/hws/hw06.tex	Fri Oct 04 11:21:30 2019 +0100
@@ -69,6 +69,14 @@
 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 Parsing combinators consist of atomic parsers, alternative
+  parsers, sequence parsers and semantic actions.  What is the purpose
+  of (1) atomic parsers and of (2) semantic actions?
+
+
+
+
 \item \POSTSCRIPT        
 \end{enumerate}