
diff -r 735f7bbfae9b -r 86c1c049eb3e hws/hw02.tex
--- a/hws/hw02.tex	Fri Sep 27 12:22:43 2013 +0100
+++ b/hws/hw02.tex	Fri Sep 27 15:05:50 2013 +0100
@@ -9,6 +9,17 @@
 \section*{Homework 2}
 
 \begin{enumerate}
+\item Review the first handout about sets of strings and read the second handout. 
+Assuming the alphabet is $\{a, b\}$, decide which of the following equations are true
+in general for arbitrary languages $A$, $B$ and $C$:
+\begin{eqnarray}
+(A \cup B) @ C & = & A @ C \cup B @ C\nonumber\\
+A^* \cup B^* & = & (A \cup B)^*\nonumber\\
A^* @ A^*  & = & A^*\nonumber\\
(A \cap B)@ C & = & (A@C) \cap (B@C)\nonumber
+\end{eqnarray}
+
+\noindent
+In case an equation is true, give an explanation; otherwise give a counter-example.
+
 \item What is the meaning of a regular expression? Give an inductive definition.
 
 \item Given the regular expressions $r_1 = \epsilon$ and $r_2 = \varnothing$ and $r_3 = a$.




