--- a/slides/slides05.tex	Tue Oct 20 00:01:56 2015 +0100
+++ b/slides/slides05.tex	Fri Oct 23 00:16:00 2015 +0100
@@ -418,9 +418,9 @@
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[c]
-\frametitle{Grammars}
+\frametitle{CF Grammars}
 
-A (context-free) grammar \bl{$G$} consists of
+A \alert{\bf context-free grammar} \bl{$G$} consists of
 
 \begin{itemize}
 \item a finite set of nonterminal symbols (upper case)
@@ -569,19 +569,22 @@
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[c]
-\frametitle{Context Sensitive Grms}
+\frametitle{\begin{tabular}{c}Context Sensitive\\[-1mm] 
+             Grammars\end{tabular}}
 
+It is much harder to find out whether a string is parsed
+by a context sensitive grammar:
 
 \begin{center}
 \bl{\begin{tabular}{lcl}
-$S$ & $\Rightarrow$ &  $bSAA\;|\; \epsilon$\\
-$A$ & $\Rightarrow$ & $a$\\
-$bA$ & $\Rightarrow$ & $Ab$\\
+$S$ & $\rightarrow$ &  $bSAA\;|\; \epsilon$\\
+$A$ & $\rightarrow$ & $a$\\
+$bA$ & $\rightarrow$ & $Ab$\\
 \end{tabular}}
 \end{center}\pause
 
 \begin{center}
-\bl{$S \Rightarrow\ldots\Rightarrow^? "ababaa"$}
+\bl{$S \rightarrow\ldots\rightarrow^? "ababaa"$}
 \end{center}
 
 \end{frame}