diff -r 11396c17cd8b -r 716042628398 cws/cw02.tex
--- a/cws/cw02.tex	Fri Nov 10 09:23:23 2017 +0000
+++ b/cws/cw02.tex	Tue Nov 14 13:14:47 2017 +0000
@@ -18,33 +18,46 @@
 
 This coursework is worth 10\%. It is about searching and
 backtracking. The first part is due on 23 November at 11pm; the
-second, more advanced part, is due on 30 November at 11pm. You are
+second, more advanced part, is due on 21 December at 11pm. You are
 asked to implement Scala programs that solve various versions of the
 \textit{Knight's Tour Problem} on a chessboard. Note the second part
 might include material you have not yet seen in the first two
-lectures.  Make sure the files you submit can be processed by just
-calling \texttt{scala <<filename.scala>>}.\bigskip
+lectures. \bigskip
 
 \noindent
-\textbf{Important:} Do not use any mutable data structures in your
-submissions! They are not needed. This means you cannot use
-\texttt{ListBuffer}s, for example. Do not use \texttt{return} in your
-code! It has a different meaning in Scala, than in Java.
-Do not use \texttt{var}! This declares a mutable variable. Feel free to
-copy any code you need from files \texttt{knight1.scala},
-\texttt{knight2.scala} and \texttt{knight3.scala}. Make sure the
-functions you submit are defined on the ``top-level'' of Scala, not
-inside a class or object. Also note that the running time of
-each part will be restricted to a maximum of 360 seconds on my
-laptop.
+\textbf{Important:}
+
+\begin{itemize}
+\item Make sure the files you submit can be processed by just calling\\
+\mbox{\texttt{scala <<filename.scala>>}} on the commandline.
+
+\item Do not use any mutable data structures in your
+submissions! They are not needed. This means you cannot use 
+\texttt{ListBuffer}s, for example. 
+
+\item Do not use \texttt{return} in your code! It has a different
+  meaning in Scala, than in Java.
 
+\item Do not use \texttt{var}! This declares a mutable variable. Only
+  use \texttt{val}!
+
+\item Do not use any parallel collections! No \texttt{.par} therefore!
+  Our testing and marking infrastructure is not set up for it.
+\end{itemize}
+
+\noindent
+Also note that the running time of each part will be restricted to a
+maximum of 360 seconds on my laptop: If you calculate a result once,
+try to avoid to calculate the result again. Feel free to copy any code
+you need from files \texttt{knight1.scala}, \texttt{knight2.scala} and
+\texttt{knight3.scala}.
  
 \subsection*{Disclaimer}
 
 It should be understood that the work you submit represents
 your own effort. You have not copied from anyone else. An
 exception is the Scala code I showed during the lectures or
-uploaded to KEATS, which you can freely use.\medskip
+uploaded to KEATS, which you can freely use.
 
 \subsection*{Background}
 
@@ -52,7 +65,6 @@
 the knight visits every field on an $n\times n$ chessboard once. For
 example on a $5\times 5$ chessboard, a knight's tour is:
 
-
 \chessboard[maxfield=d4, 
             pgfstyle= {[base,at={\pgfpoint{0pt}{-0.5ex}}]text},
             text = \small 24, markfield=Z4,
@@ -81,7 +93,7 @@
             text = \small 21, markfield=c0,
             text = \small  2, markfield=d0
            ]
-
+           
 \noindent
 The tour starts in the right-upper corner, then moves to field
 $(3,2)$, then $(4,0)$ and so on. There are no knight's tours on