--- a/slides/slides05.tex	Sat May 05 10:31:00 2018 +0100
+++ b/slides/slides05.tex	Fri Jun 01 15:28:37 2018 +0100
@@ -478,6 +478,25 @@
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[c]
+\frametitle{What Parsing is Not}
+
+Usually parsing does not check semantic correctness, e.g.
+
+\begin{itemize}
+\item  whether a function is not used before it
+  is defined
+\item whether a function has the correct number of arguments 
+  or are of correct type
+\item whether a variable can be declared twice in a scope  
+\end{itemize}  
+
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
+
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[c]
 \frametitle{Regular Languages}
 
 While regular expressions are very useful for lexing, there is