--- a/handouts/ho02.tex	Thu Dec 31 23:40:48 2015 +0000
+++ b/handouts/ho02.tex	Tue Jan 05 01:46:41 2016 +0000
@@ -14,7 +14,7 @@
 than the matchers from regular expression libraries in Ruby
 and Python (the plots on the left). These plots show the
 running time for the evil regular expression
-$a^?^{\{n\}}\cdot a^{\{n\}}$ and strings composed of $n$ \pcode{a}s.
+$a^?{}^{\{n\}}\cdot a^{\{n\}}$ and strings composed of $n$ \pcode{a}s.
 We will use this regular expression and strings as running
 example. To see the substantial differences in the two plots
 below, note the different scales of the $x$-axes. 
@@ -413,7 +413,7 @@
 \end{figure}
 
 For running the algorithm with our favourite example, the evil
-regular expression $a^?^{\{n\}}a^{\{n\}}$, we need to implement
+regular expression $a^?{}^{\{n\}}a^{\{n\}}$, we need to implement
 the optional regular expression and the exactly $n$-times
 regular expression. This can be done with the translations