diff -r 1efa38ee7237 -r ea594f94f85d hw03.tex
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hw03.tex	Tue Oct 09 21:19:47 2012 +0100
@@ -0,0 +1,33 @@
+\documentclass{article}
+\usepackage{charter}
+\usepackage{hyperref}
+\usepackage{amssymb}
+\usepackage{amsmath}
+
+\begin{document}
+
+\section*{Homework 3}
+
+\begin{enumerate}
+\item Assume you have an alphabet consisting of the letters $a$, $b$ and $c$ only.
+(a) Find a regular expression that recognises the two strings $ab$ and $ac$. (b)
+Find a regular expression that matches all strings \emph{except} these two strings.
+Note, you can only use regular expressions of the form 
+\begin{center}
+$r ::= \varnothing \;|\; \epsilon \;|\; c  \;|\; r_1 + r_2  \;|\; r_1 \cdot r_2 \;|\; r^*$
+\end{center}
+
+\item Define the function $zeroable$ which takes a regular expression as argument
+and returns an integer. The function should satisfy the following property:
+\begin{center}
+$zeroable(r)$ \;if and only if\; $L(r) = \varnothing$
+\end{center}
+
+\end{enumerate}
+
+\end{document}
+
+%%% Local Variables: 
+%%% mode: latex
+%%% TeX-master: t
+%%% End: