--- a/slides/slides07.tex	Mon Nov 11 23:24:38 2013 +0000
+++ b/slides/slides07.tex	Tue Nov 12 21:51:57 2013 +0000
@@ -106,7 +106,7 @@
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}CFGs\end{tabular}}
+\frametitle{\begin{tabular}{c}Two Weeks Ago: CFGs\end{tabular}}
 
 A \alert{context-free} grammar (CFG) \bl{$G$} consists of:
 
@@ -130,7 +130,7 @@
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Hierarchie of Languages\end{tabular}}
+\frametitle{\begin{tabular}{c}Hierarchy of Languages\end{tabular}}
 
 Recall that languages are sets of strings.