diff -r 3b9496db3fb9 -r 3390e863d796 hws/hw01.tex
--- a/hws/hw01.tex	Tue Sep 26 14:07:29 2017 +0100
+++ b/hws/hw01.tex	Tue Sep 26 14:08:49 2017 +0100
@@ -29,10 +29,11 @@
 
 \item Read the handout of the first lecture and the handout
       about notation. Make sure you understand the concepts of
-      strings and languages. In the context of the AFL-course,
+      strings and languages. In the context of the CFL-course,
       what is meant by the term \emph{language}?
 
-\item Give the definition for regular expressions. What is the
+    \item Give the definition for regular expressions---this is an
+      inductive datatype. What is the
       meaning of a regular expression? (Hint: The meaning is
       defined recursively.)
 
@@ -41,6 +42,7 @@
       \emph{concatenating} two sets of strings. This operation
       is also written as $\_ \,@\, \_$. According to 
       this definition, what is $A \,@\, \{\}$ equal to?
+      Is in general $A\,@\,B$ equal to $B\,@\,A$?
 
 \item Assume a set $A$ contains 4 strings and a set $B$
       contains 7 strings. None of the strings is the empty