# HG changeset patch
# User Christian Urban <christian dot urban at kcl dot ac dot uk>
# Date 1381135511 -3600
# Node ID 04264d0c43bb4ac7db9069ad423c7dc69faecf1b
# Parent  13ff10d9717ab0affcf4dff0887b4c3c36e698b4
added

diff -r 13ff10d9717a -r 04264d0c43bb hws/hw01.pdf
Binary file hws/hw01.pdf has changed
diff -r 13ff10d9717a -r 04264d0c43bb hws/hw02.pdf
Binary file hws/hw02.pdf has changed
diff -r 13ff10d9717a -r 04264d0c43bb hws/hw02.tex
--- a/hws/hw02.tex	Mon Oct 07 09:34:12 2013 +0100
+++ b/hws/hw02.tex	Mon Oct 07 09:45:11 2013 +0100
@@ -14,7 +14,9 @@
 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
+A^* \cup B^* & = & (A \cup B)^*\nonumber\\
+A^* @ A^*  & = & A^*\nonumber\\
+(A \cap B)@ C & = & (A@C) \cap (B@C)\nonumber
 \end{eqnarray}
 
 \noindent
@@ -36,8 +38,6 @@
 \item Given the regular expression $r = (a \cdot b + b)^*$. Compute what the derivative of $r$ is with respect to
 $a$ and $b$. Is $r$ nullable?
 
-\item What is a regular language?
-
 \item Prove that for all regular expressions $r$ we have
 \begin{center}
 $\text{nullable}(r)$ \quad if and only if \quad $\texttt{""} \in L(r)$
diff -r 13ff10d9717a -r 04264d0c43bb hws/hw03.pdf
Binary file hws/hw03.pdf has changed
diff -r 13ff10d9717a -r 04264d0c43bb hws/hw03.tex
--- a/hws/hw03.tex	Mon Oct 07 09:34:12 2013 +0100
+++ b/hws/hw03.tex	Mon Oct 07 09:45:11 2013 +0100
@@ -9,6 +9,8 @@
 \section*{Homework 3}
 
 \begin{enumerate}
+\item What is a regular language?
+
 \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.
@@ -18,7 +20,7 @@
 \end{center}
 
 \item Define the function $zeroable$ which takes a regular expression as argument
-and returns a boolean.\footnote{In an earlier version there was an error.} The 
+and returns a boolean. The 
 function should satisfy the following property:
 \begin{center}
 $zeroable(r)$ \;if and only if\; $L(r) = \varnothing$