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\title{Tytuł} 
\author{Franciszek Malinka}

\begin{document}
  \begin{abstract} 
    Abstract 
  \end{abstract} 
  \section{Introduction}
  \subfile{sections/introduction}

  \section{Preliminaries} 
  \subfile{sections/preliminaries}

  \section{Fraïssé classes}
  \subfile{sections/fraisse_classes}

  \section{Conjugacy classes in automorphism groups}
  \subfile{sections/conj_classes}

  \printbibliography
\end{document}