diff -r 65731df141a5 -r 08b5ddbc7e55 cws/cw04.tex
--- a/cws/cw04.tex	Wed Oct 30 14:07:58 2019 +0000
+++ b/cws/cw04.tex	Wed Oct 30 14:21:16 2019 +0000
@@ -106,7 +106,7 @@
 This coursework is about the shunting yard algorithm by Dijkstra and a
 regular expression matcher by Brzozowski. The preliminary part is due on
 \cwNINE{} at 4pm; the core, more advanced part, is due on \cwNINEa{}
-at 4pm. The preliminary part is about the shunting yard algorithm that
+at 4pm. The preliminary part is about the Shunting Yard Algorithm that
 transforms the usual infix notation of arithmetic expressions into the
 postfix notation, which is for example used in compilers. In the core
 part, you are asked to implement a regular expression matcher based on
@@ -142,7 +142,7 @@
 
 \begin{lstlisting}[xleftmargin=1mm,numbers=none,basicstyle=\ttfamily\small]
 $ scala -cp re.jar
-scala> import CW9a._  
+scala> import CW9c._  
 scala> for (i <- 0 to 5000000 by 500000) {
   | println(i + " " + "%.5f".format(time_needed(2, matcher(EVIL, "a" * i))) + "secs.")
   | }
@@ -257,7 +257,7 @@
 \subsubsection*{Task (file postfix2.scala)}
 
 \begin{itemize}
-\item[(3)] Extend the code in (7) and (8) to include the power
+\item[(3/4)] Extend the code in (7) and (8) to include the power
   operator.  This requires proper account of associativity of
   the operators. The power operator is right-associative, whereas the
   other operators are left-associative.  Left-associative operators
@@ -300,9 +300,10 @@
 
 {\small
 \begin{itemize}
-\item[$\bullet$] \url{http://stackstatus.net/post/147710624694/outage-postmortem-july-20-2016}
+\item[$\bullet$] \url{https://blog.cloudflare.com/details-of-the-cloudflare-outage-on-july-2-2019}  
+\item[$\bullet$] \url{https://stackstatus.net/post/147710624694/outage-postmortem-july-20-2016}
 \item[$\bullet$] \url{https://vimeo.com/112065252}
-\item[$\bullet$] \url{http://davidvgalbraith.com/how-i-fixed-atom/}  
+\item[$\bullet$] \url{https://davidvgalbraith.com/how-i-fixed-atom}  
 \end{itemize}}
 
 % Knowing how to match regular expressions and strings will let you
@@ -350,7 +351,7 @@
 
 \item[(6)] Implement a function, called \textit{der}, by recursion over
   regular expressions. It takes a character and a regular expression
-  as arguments and calculates the derivative of a xregular expression according
+  as arguments and calculates the derivative of a regular expression according
   to the rules:
 
 \begin{center}
@@ -485,7 +486,7 @@
 taking the derivative, but simplify the result.  The sizes
 are given in \texttt{re.scala}. \hfill[1 Mark]
 
-\item[(6)] You do not have to implement anything specific under this
+\item[(10)] You do not have to implement anything specific under this
   task.  The purpose here is that you will be marked for some ``power''
   test cases. For example can your matcher decide within 30 seconds
   whether the regular expression $(a^*)^*\cdot b$ matches strings of the