JJ3mp2
Written on June 24, 2019
% Dans le préambule
% -----------------
\usepackage{tikz}
% -----------------
\begin{tikzpicture}
\matrix[nodes={draw,circle}, row sep=0.5cm,
column sep=0.5cm] {
\node (a){1}; &\node (c){3}; & ;\\
\node (b){2}; & ; &\node (d){4} ;\\ };
\tikzstyle{fleche} = [draw,thick,->,>=latex]
\draw[fleche] (b) -- (a);
\draw[fleche] (c) -- (a);
\draw[fleche] (b) -- (c);
\draw[fleche] (c) to[bend right] (d);
\draw[fleche] (d) to[bend right] (c);
\end{tikzpicture}