\documentclass[hyperref={pdfpagelabels=false},greek]{beamer}


\mode<presentation>
{
%\usetheme{default}\usecolortheme{beaver}%\useoutertheme{default}
%\usetheme{PaloAlto}
  \usetheme{Warsaw} %<-- Well known blue theme
% \usetheme{Berlin}
%\usecolortheme{seahorse}
%\usecolortheme{rose}
%\usetheme{Berkeley}
%\usetheme{boxes}
%\usetheme{Antibes}
% \usetheme{Bergen}
%\usetheme{CambridgeUS} %<-- Simpler themes I like
% \usetheme{Copenhagen}
% \usetheme{Darmstadt}
% \usetheme{Dresden}
% \usetheme{Frankfurt}
% \usetheme{Goettingen} %<-- Simpler themes I like
% \usetheme{Hannover}
% \usetheme{Ilmenau}
% \usetheme{JuanLesPins}
% \usetheme{Luebeck}
% \usetheme{Madrid}
% \usetheme{Malmoe}
% \usetheme{Marburg} %<-- Simpler themes I like
% \usetheme{Montpellier}
% \usetheme{Pittsburgh}
% \usetheme{Rochester}
% \usetheme{Singapore} %<-- Simpler themes I like
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%\usetheme{Boadilla}
%\usetheme{AnnArbor}

%%% remove beamer's navigation bar!! %%%%%%
% \setbeamertemplate{navigation symbols}{} %% 
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%%%% Comment to completely cover next transparencies %%
%\setbeamercovered{transparent} %%%%%%%%%%%%%%%%%%%%%%%%
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}

%%-----------------------------------------------------------------------------
% Languages
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\usepackage{xgreek}
\usepackage[Greek,Latin]{ucharclasses}
\setTransitionsForGreek{\setlanguage{greek}}{\setlanguage{english}}

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% Fonts
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%\usepackage{fontspec}
%\setmainfont{Minion Pro} % substitute with any font that exists on your system
%\setsansfont{GFSNeohellenic.otf} % substitute with any font that exists on your system
%\setmonofont{Consolas} % substitute with any font that exists on your system
\usepackage[gfsneohellenic]{fontsetup}
\setsansfont[% main font
	 UprightFont=GFSNeohellenic,
         ItalicFont=GFSNeohellenicIt,
	 BoldFont=GFSNeohellenicBold,
	 BoldItalicFont=GFSNeohellenicBoldIt,	 
          RawFeature=+pnum,% variable width numbers
       WordSpace={0.75,0.75,1},%
       Scale=1.2%use instead of 12pt 
]{GFSNeohellenic.otf}
\usefonttheme{professionalfonts}

%%-----------------------------------------------------------------------------
% Beamer Stuff
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\title[Σύντομος τίτλος]{Η ομιλία μου: Γενικός Τίτλος}
\author[Α.\ Τσολομύτης] % (optional, use only with lots of authors)
{Αντώνης Τσολομύτης}

\institute[Πανεπιστήμιο Αιγαίου] % (optional, but mostly needed)
{
  Τμήμα Μαθηματικών\\
  Πανεπιστήμιο Αιγαίου\\[4ex]
κοινή εργασία με τους Συνεργάτης 1 και Συνεργάτης 2. 
}
\date{Μάρτιος, \textsc{2018}}
\usepackage{hyperref}
\usepackage{amsfonts,amssymb,wasysym}
\usepackage[accumulated]{beamerseminar}
\usepackage{beamertexpower}

\makeatletter
\newcommand{\arccot}{\mathop{\operator@font arccot}}
\makeatother


%%%%%% Add more theorem environments below as needed %%%%
\uselanguage{xgreek}
\languagepath{xgreek}
\deftranslation[to=xgreek]{Theorem}{Θεώρημα}
\deftranslation[to=xgreek]{theorem}{θεώρημα}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


\begin{document}


\begin{frame}
\titlepage
\end{frame}



%\section{}




\begin{frame}
 \frametitle{Συμβολισμός}

Κάθε σελίδα είναι ένα frame. Παύση μέσα σε κάθε frame
γίνεται με την εντολή \textbackslash{}pause
\pause
\begin{equation*}
\arccot 0=\pause\pi/2.
\end{equation*}



\pause

Θεωρούμε\ldots
\end{frame}


\begin{frame}
\frametitle{Το κύριο θεώρημα}
\begin{theorem} Ισχύει $$\sum_{j=1}^n\int_{\mathbb S^{n-1}} |x_j|^2\,d\sigma(x)=1.$$
\end{theorem}
\end{frame}



\end{document}



\begin{frame}
\titlepage
\end{frame} 

\section{Κεφάλαιο 1ο}

\begin{frame}
\frametitle{Αυτό είναι το 1ο κεφάλαιο} 
Συμπληρώνεις ανάλογα! 
\end{frame}

\end{document}
