--- a/cws/cw06.tex	Tue May 15 01:14:07 2018 +0100
+++ b/cws/cw06.tex	Tue May 15 10:57:20 2018 +0100
@@ -69,14 +69,15 @@
 \noindent
 The problem is to calculate a sequence of steps to reach the end of
 the list by taking only steps indicated by the integers. For the list
-above, possible sequence of steps are 3 - 2 - 1 - End, but also 3 - 4
+above, possible sequences of steps are 3 - 2 - 1 - End, but also 3 - 4
 - End.  This is a recursive problem that can be thought of as a tree
 where the root is a list and the children are all the lists that are
 reachable by a single step. For example for the list above this gives a
 tree like
 
 \begin{center}
-\begin{tikzpicture}[grow=right,level distance=30mm,child anchor=north]
+  \begin{tikzpicture}
+    [grow=right,level distance=30mm,child anchor=north,line width=0.5mm]
   \node {[3,4,2,0,1]}
      child {node {[0,1]}}
      child {node {[2,0,1]}