\documentclass[11pt]{article}

% ATTENTION: SI VOUS UTILISEZ DES LETTRES ACCENTUEES, VOTRE EDITEUR DOIT UTILISER L'ENCODAGE UTF8
\usepackage[utf8]{inputenc} % accents
\usepackage{t1enc}
\usepackage{latexsym}
\usepackage{graphicx}         % pour d'éventuelles figures
\usepackage{amsmath,amssymb,amsfonts}          % AMSTEX
\usepackage{a4wide}
\usepackage{fancyhdr}

\parindent=0cm

\renewcommand{\refname}{R\'ef\'erences}
\renewcommand{\headrulewidth}{0pt}

\newcommand{\titre}[1]{%
  \begin{center}
    {\Large{\bf #1}}
  \end{center}%
  }

\newcommand{\orateur}[2]{%
  \begin{center}
    {\underline{\large{\bf #1}}}\\
    {#2}
  \end{center}%
}

\newcommand{\auteur}[2]{%
  \begin{center}
    {\large{\bf #1}}\\
    {#2}
  \end{center}%
}

\newcommand{\motsclefs}[1]{\noindent{\large{\bf Mots-clefs :}} #1\\}

\long\def\resume#1{
   \vskip1em
  {\centering \begin{minipage}{0.8\linewidth}
    {\bf Résumé.}#1
  \end{minipage}
  \par}
  \vskip2em
}

\newcommand{\BiblioItem}[4]{\bibitem{#1} {\sc #2}. {\sl #3}. #4. }

\begin{document}

\pagestyle{fancy}

\lhead{Journées SMAI MODE 2018} \rhead{}
\cfoot{}

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%                                                                          %
%        Merci de fournir les informations                                 %
%                                                                          %
%       titre, orateur, auteur, résumé et mots clefs                       %
%                                                                          %
%       en utilisant les commandes ci-dessous                              %
%                                                                          %
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\titre{VOTRE TITRE ICI}

\orateur{Prénom NOM}{Université de ...}

% Pour chaque co-auteur, ajouter une entrée
\auteur{Prénom NOM}{Université de ....}

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% Recopier le contenu de la commande \resume dans le champ résumé du       %
% formulaire de soumission.                                                %
% Vous pouvez utiliser des commandes mathématiques de base, mais aucune    %
% macros personnelles.                                                     %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\resume{
 Mon résumé.
}

% mots-clefs 
\motsclefs{vos mots clefs.}


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%                   DEBUT DE LA COMMUNICATION                              %
%                                                                          %
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%               REFERENCES BIBLIOGRAPHIQUES                                %
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\bibliographystyle{plain}

\begin{thebibliography}{99}

\BiblioItem{ref1}{P. Nom, P. Nom}{Titre}{Journal, informations de publication}

\end{thebibliography}

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\end{document}
