\begin{figure}[H]
  \begin{center}
    \unitlength=4pt
    \begin{picture}(15, 30)(0,-6)
    \gasset{Nw=5,Nh=5,Nmr=2.5,curvedepth=4}
    \thinlines
    \node[Nmarks=if,iangle=180,fangle=180](A0)(0,8.66){$0$}
    \node(A1)(15,17.32){$1$}
    \node(A2)(15,0){$2$}
    \drawedge(A0,A1){$a$}
    \drawedge(A1,A2){$a$}
    \drawedge(A2,A0){$a,b$}
    \drawedge(A1,A0){$b$}
    \drawloop[loopangle=60](A1){$b$}
    \drawloop[loopangle=-60](A2){$b$}
    \end{picture}
  \end{center}
  \caption{Un automate non déterministe.}
\end{figure}