--- a/slides/slides06.tex	Wed Nov 06 21:52:42 2019 +0000
+++ b/slides/slides06.tex	Wed Nov 06 23:17:05 2019 +0000
@@ -28,9 +28,10 @@
   \normalsize
   \begin{center}
   \begin{tabular}{ll}
-  Email:  & christian.urban at kcl.ac.uk\\
-  Office: & N\liningnums{7.07} (North Wing, Bush House)\\
-  Slides: & KEATS (also homework is there)\\
+    Email:  & christian.urban at kcl.ac.uk\\
+    Office Hours: & Thursdays 12 -- 14\\
+    Location: & N7.07 (North Wing, Bush House)\\
+    Slides \& Progs: & KEATS (also homework is there)\\  
   \end{tabular}
   \end{center}
 
@@ -86,8 +87,23 @@
 % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[t]
+\frametitle{Starting Symbol}
+
+\bl{\begin{plstx}[margin=1cm]
+  : \meta{S} ::= \meta{A}\cdot\meta{S}\cdot\meta{B} |
+                 \meta{B}\cdot\meta{S}\cdot\meta{A} | \epsilon\\
+  : \meta{A} ::= a | \epsilon\\
+  : \meta{B} ::= b\\  
+\end{plstx}}
+
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Hierarchy of Languages\end{tabular}}
+\frametitle{Hierarchy of Languages}
 
 Recall that languages are sets of strings.