# HG changeset patch
# User Christian Urban <christian dot urban at kcl dot ac dot uk>
# Date 1380290750 -3600
# Node ID 86c1c049eb3edf1865deb11caeeeaa9ec4830f73
# Parent  735f7bbfae9bec23971fd1d62db9c99dac83b4b9
updated

diff -r 735f7bbfae9b -r 86c1c049eb3e hws/hw01.pdf
Binary file hws/hw01.pdf has changed
diff -r 735f7bbfae9b -r 86c1c049eb3e hws/hw01.tex
--- a/hws/hw01.tex	Fri Sep 27 12:22:43 2013 +0100
+++ b/hws/hw01.tex	Fri Sep 27 15:05:50 2013 +0100
@@ -17,6 +17,8 @@
 
 \item {\bf (Optional)} Have a look at the crawler programs. 
 Can you find a usage for them in your daily programming life?
+Can you improve them (in cases they are linked on different levels, 
+they visit web-pages several times)? 
 
 \item Read the handout of the first lecture and make sure you
 understand the concepts of strings and languages. 
diff -r 735f7bbfae9b -r 86c1c049eb3e hws/hw02.pdf
Binary file hws/hw02.pdf has changed
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 $r_3 = a$.