--- a/slides/slides02.tex	Fri Sep 25 10:17:11 2020 +0100
+++ b/slides/slides02.tex	Sat Sep 26 23:45:40 2020 +0100
@@ -178,7 +178,8 @@
   
    \begin{bubble}[10cm]
     \large
-    Two regular expressions \bl{$r_1$} and \bl{$r_2$} are equivalent 
+    Two regular expressions \bl{$r_1$} and \bl{$r_2$} are
+    \alert{\bf{}equivalent} 
     provided:\medskip 
     \begin{center}
       \bl{$r_1 \equiv r_2 \;\;\dn\;\; L(r_1) = L(r_2)$}  
@@ -243,29 +244,6 @@
 \end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
   
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\begin{frame}[c]
-\frametitle{The Specification for Matching}
-
-\begin{bubble}[10cm]
-\large
-A regular expression \bl{$r$} matches a string~\bl{$s$} 
-provided:
-\begin{center}
-\bl{$s \in L(r)$} 
-\end{center}\medskip
-\end{bubble}
-
-\bigskip\bigskip
-
-\ldots and the point of the this lecture is to decide this problem as
-fast as possible (unlike Python, Ruby, Java etc)
-
-\end{frame}
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
-  
-
-
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[t]
@@ -301,6 +279,27 @@
 \end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[c]
+\frametitle{The Specification for Matching}
+
+\begin{bubble}[10cm]
+\large
+A regular expression \bl{$r$} matches a string~\bl{$s$} 
+provided:
+\begin{center}
+\bl{$s \in L(r)$} 
+\end{center}\medskip
+\end{bubble}
+
+\bigskip\bigskip
+
+\ldots and the point of the this lecture is to decide this problem as
+fast as possible (unlike Python, Ruby, Java etc)
+
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
+  
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[c]