--- a/slides.sty	Sat Oct 01 23:34:37 2016 +0100
+++ b/slides.sty	Sun Oct 02 14:07:42 2016 +0100
@@ -18,6 +18,10 @@
 
 \newcommand{\ZERO}{\mbox{\bf 0}}
 \newcommand{\ONE}{\mbox{\bf 1}}
+\newcommand{\Der}{\textit{Der}}
+\newcommand{\der}{\textit{der}}
+\newcommand{\Ders}{\textit{Ders}}
+\newcommand{\ders}{\textit{ders}}
 \newcommand{\dn}{\stackrel{\mbox{\scriptsize def}}{=}}%
 \newcommand{\slidecaption}{}