Binary file slides/slides04.pdf has changed

--- a/slides/slides04.tex	Tue Oct 21 08:41:46 2025 +0200
+++ b/slides/slides04.tex	Tue Oct 21 17:09:56 2025 +0200
@@ -446,35 +446,35 @@
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
-% {
-% \setbeamercolor{background canvas}{bg=cream}
-% \begin{frame}[c]
-% \small
+{
+\setbeamercolor{background canvas}{bg=cream}
+\begin{frame}[c,fragile]
+\small
 
-% \begin{lstlisting}[language=Scala,numbers=none]
-% enum Rexp {
-%   case ZERO
-%   case ONE
-%   case CHAR(c: Char)
-%   case ALT(r1: Rexp, r2: Rexp)
-%   case SEQ(r1: Rexp, r2: Rexp)
-%   case STAR(r: Rexp)
-% }
-% \end{lstlisting}
+\begin{lstlisting}[language=Scala,numbers=none]
+ enum Rexp {
+   case ZERO
+   case ONE
+   case CHAR(c: Char)
+   case ALT(r1: Rexp, r2: Rexp)
+   case SEQ(r1: Rexp, r2: Rexp)
+   case STAR(r: Rexp)
+}
+\end{lstlisting}
 
-% \begin{lstlisting}[language=Scala,numbers=none]
-% enum Val {
-%   case Empty
-%   case Chr(c: Char)
-%   case Sequ(v1: Val, v2: Val)
-%   case Left(v: Val)
-%   case Right(v: Val)
-%   case Stars(vs: List[Val])
-% }
-% \end{lstlisting}
+\begin{lstlisting}[language=Scala,numbers=none]
+enum Val {
+   case Empty
+   case Chr(c: Char)
+   case Sequ(v1: Val, v2: Val)
+   case Left(v: Val)
+   case Right(v: Val)
+   case Stars(vs: List[Val])
+}
+\end{lstlisting}
 
-% \end{frame}
-% }
+\end{frame}
+}
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[c]