\documentclass[crop,tikz]{standalone}
\input{common-headers}
\input{sigles}

\begin{document}

\begin{tikzpicture}[scale=2,
  model/.style={draw},
  system/.style={draw},
  arrowed/.style={auto,-Stealth,shorten <=2pt,shorten >=2pt,bend angle=10},
  darowed/.style={auto,double,Stealth-Stealth,shorten <=2pt,shorten >=2pt},
  validate/.style={arrowed},
  validate2/.style={arrowed,dashed},
  annotation/.style={font=\scriptsize}]
  
  \node[model] (F) at ( 1cm, 0) {Formalisme};
  \node[model] (M) at ( -1cm, 0) {Modèle};
  
  \draw[validate] (F) to node[annotation,swap] {permet d'exprimer} (M);
  %\draw[validate,bend right] (M1) to node[annotation,swap] {validation} (W);
  
  % Separation
  \draw[dashed] (-1.5cm,-0.5cm) to ( 2.5cm,-0.5cm);
  \coordinate (legend) at (2,-0.5cm);
  \node at (legend) [label=north:{Abstrait}] {};
  \node at (legend) [label=south:{Concret}] {};
  
  \node[system] (S) at ( 0cm,-1cm) {Système};
  \draw[darowed] (M) to node[annotation,yshift=2pt] {explique} (S);
\end{tikzpicture}

\end{document}