\documentclass[14pt]{beamer}

% beamer definieert 'definition' al, maar dan engels :(
% fix van:
% http://tex.stackexchange.com/questions/38392/how-to-rename-theorem-or-lemma-in-beamer-to-another-language
\usepackage[dutch]{babel}
\uselanguage{dutch}
\languagepath{dutch}
\deftranslation[to=dutch]{Definition}{Definitie}

\newcommand{\spc}[0]{\hspace{0.5cm}}

\input{../thesis/preamble}

\begin{document}


\begin{frame}
$$ \cat{C} \cat{D} $$
$$ A B C X Y Z $$
$$ F(A) F(B) F(C) $$
\small $$ f g g \circ f $$
\small $$ F(f) F(g) $$
\end{frame}

\end{document}