
diff -r 1e4da6d2490c -r e5f4b8ff23b8 coursework/cw01.tex
--- a/coursework/cw01.tex	Fri Sep 26 14:06:55 2014 +0100
+++ b/coursework/cw01.tex	Fri Sep 26 14:40:49 2014 +0100
@@ -6,23 +6,34 @@
 
 \section*{Coursework 1}
 
-This coursework is worth 3\% and is due on 12 November at 16:00. You are asked to implement 
-a regular expression matcher and submit a document containing the answers for the questions 
-below. You can do the implementation in any programming language you like, but you need 
-to submit the source code with which you answered the questions. However, the coursework 
-will \emph{only} be judged according to the answers. You can submit your answers
-in a txt-file or pdf.\bigskip
+This coursework is worth 5\% and is due on 13 October at 16:00. You
+are asked to implement a regular expression matcher and submit a
+document containing the answers for the questions below. You can do
+the implementation in any programming language you like, but you need
+to submit the source code with which you answered the
+questions. However, the coursework will \emph{only} be judged
+according to the answers. You can submit your answers in a txt-file or
+pdf.
+
+\subsubsection*{Disclaimer}
 
-\noindent
-The task is to implement a regular expression matcher based on derivatives. The implementation 
-should be able to deal with the usual regular expressions
+It should be understood that the work submitted represents your own effort. 
+You have not copied from anyone else. An exception is the Scala code I
+showed during the lectures, which you can use.\bigskip
+
+
+\subsubsection*{Tasks}
+
+The task is to implement a regular expression matcher based on
+derivatives. The implementation should be able to deal with the usual
+(basic) regular expressions
 
 \[
 \varnothing, \epsilon, c, r_1 + r_2, r_1 \cdot r_2, r^*
 \]
 
 \noindent
-but also with
+but also with the following extended regular expressions:
 
 \begin{center}
 \begin{tabular}{ll}
@@ -40,38 +51,67 @@
 
 \begin{center}
 \begin{tabular}{r@{\hspace{2mm}}c@{\hspace{2mm}}l}
-$L([c_1 c_2 \ldots c_n])$ & $\dn$ & $\{"c_1", "c_2", \ldots, "c_n"\}$\\ 
-$L(r^+)$            & $\dn$ & $\bigcup_{1\le i}. L(r)^i$\\
-$L(r^?)$            & $\dn$ & $L(r) \cup \{""\}$\\
-$L(r^{\{n,m\}})$ & $\dn$ & $\bigcup_{n\le i \le m}. L(r)^i$\\
-$L(\sim{}r)$       & $\dn$ & $UNIV - L(r)$
+$L([c_1 c_2 \ldots c_n])$ & $\dn$ & $\{[c_1], [c_2], \ldots, [c_n]\}$\\ 
+$L(r^+)$                  & $\dn$ & $\bigcup_{1\le i}. L(r)^i$\\
+$L(r^?)$                  & $\dn$ & $L(r) \cup \{[]\}$\\
+$L(r^{\{n,m\}})$           & $\dn$ & $\bigcup_{n\le i \le m}. L(r)^i$\\
+$L(\sim{}r)$              & $\dn$ & $\mathbb{A} - L(r)$
 \end{tabular}
 \end{center}
 
 \noindent
-whereby in the last clause the set $UNIV$ stands for the set of \emph{all} strings.
-So $\sim{}r$ means `all the strings that $r$ cannot match'. We assume ranges 
-like $[a\mbox{-}z0\mbox{-}9]$ are a shorthand for the regular expression
+whereby in the last clause the set $\mathbb{A}$ stands for the set of
+\emph{all} strings.  So $\sim{}r$ means `all the strings that $r$
+cannot match'. We assume ranges like $[a\mbox{-}z0\mbox{-}9]$ are a
+shorthand for the regular expression
 
 \[
 [a b c d\ldots z 0 1\ldots 9]\;.
 \]
 
 \noindent 
-Be careful that your implementation of $nullable$ and $der$ satisfies for every $r$ the following two
-properties:
+Be careful that your implementation of $nullable$ and $der$ satisfies
+for every $r$ the following two properties:
 
 \begin{itemize}
-\item $nullable(r)$ if and only if $""\in L(r)$
+\item $nullable(r)$ if and only if $[]\in L(r)$
 \item $L(der\,c\,r)) = Der\,c\,(L(r))$
 \end{itemize}
-\newpage
+
+\noindent
+{\bf Important!} Your implementation should have explicit cases for the
+basic regular expressions, but also for the extended regular expressions.
+That means do not treat the extended regular expressions by just translating 
+them into the basic ones. See also Question 2, where you asked to give
+the rules for \textit{nullable} and \textit{der}.
+
 
 \subsection*{Question 1 (unmarked)}
 
-What is your King's email address (you will need it in the next question)?\bigskip 
+What is your King's email address (you will need it in Question 2)?
+
+\subsection*{Question 2 (marked with 2\%)}
+
+This question does not require any implementation. From the lectures
+you have seen the definitions for the functions \textit{nullable} and
+\textit{der}.  Give the rules for the extended regular expressions:
 
-\subsection*{Question 2 (marked with 1\%)}
+\begin{center}
+\begin{tabular}{@ {}l@ {\hspace{2mm}}c@ {\hspace{2mm}}l@ {}}
+$nullable([c_1 c_2 \ldots c_n])$  & $\dn$ & $?$\\
+$nullable(r^+)$                   & $\dn$ & $?$\\
+$nullable(r^?)$                   & $\dn$ & $?$\\
+$nullable(r^{\{n,m\}})$            & $\dn$ & $?$\\
+$nullable(\sim{}r)$               & $\dn$ & $?$\medskip\\
+$der c ([c_1 c_2 \ldots c_n])$  & $\dn$ & $?$\\
+$der c (r^+)$                   & $\dn$ & $?$\\
+$der c (r^?)$                   & $\dn$ & $?$\\
+$der c (r^{\{n,m\}})$            & $\dn$ & $?$\\
+$der c (\sim{}r)$               & $\dn$ & $?$\\
+\end{tabular}
+\end{center}
+
+\subsection*{Question 3 (marked with 1\%)}
 
 Implement the following regular expression for email addresses
 
@@ -80,9 +120,10 @@
 \]
 
 \noindent
-and calculate the derivative according to your email address. When calculating
-the derivative, simplify all regular expressions as much as possible, but at least apply the following 
-six simplification rules:
+and calculate the derivative according to your email address. When
+calculating the derivative, simplify all regular expressions as much
+as possible, but at least apply the following six simplification
+rules:
 
 \begin{center}
 \begin{tabular}{l@{\hspace{2mm}}c@{\hspace{2mm}}l}
@@ -96,12 +137,15 @@
 \end{center}
 
 \noindent
-Write down your simplified derivative in the ``mathematicical'' notation using parentheses where necessary.
+Write down your simplified derivative in the ``mathematicical''
+notation using parentheses where necessary.
+
+\subsection*{Question 4 (marked with 1\%)}
 
-\subsection*{Question 3 (marked with 1\%)}
-
-Consider the regular expression $/ \cdot * \cdot (\sim{}([a\mbox{-}z]^* \cdot * \cdot / \cdot [a\mbox{-}z]^*)) \cdot * \cdot /$ and decide
-wether the following four strings are matched by this regular expression. Answer yes or no.
+Consider the regular expression $/ \cdot * \cdot
+(\sim{}([a\mbox{-}z]^* \cdot * \cdot / \cdot [a\mbox{-}z]^*)) \cdot *
+\cdot /$ and decide wether the following four strings are matched by
+this regular expression. Answer yes or no.
 
 \begin{enumerate}
 \item \texttt{"/**/"}
@@ -110,16 +154,18 @@
 \item \texttt{"/*test/*test*/"}
 \end{enumerate}
 
-\subsection*{Question 4 (marked with 1\%)}
+\subsection*{Question 5 (marked with 1\%)}
 
-Let $r_1$ be the regular expression $a\cdot a\cdot a$ and $r_2$ be $(a^{\{19,19\}}) \cdot (a^?)$.
-Decide whether the following three strings consisting of $a$s only can be matched by $(r_1^+)^+$. 
-Similarly test them with $(r_2^+)^+$. Again answer in all six cases with yes or no. \medskip
+Let $r_1$ be the regular expression $a\cdot a\cdot a$ and $r_2$ be
+$(a^{\{19,19\}}) \cdot (a^?)$.  Decide whether the following three
+strings consisting of $a$s only can be matched by $(r_1^+)^+$.
+Similarly test them with $(r_2^+)^+$. Again answer in all six cases
+with yes or no. \medskip
 
 \noindent
-These are strings are meant to be entirely made up of $a$s. Be careful when 
-copy-and-pasting the strings so as to not forgetting any $a$ and to not introducing any
-other character.
+These are strings are meant to be entirely made up of $a$s. Be careful
+when copy-and-pasting the strings so as to not forgetting any $a$ and
+to not introducing any other character.
 
 \begin{enumerate}
 \item \texttt{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\\




