\begin{figure}[H]
  \begin{center}
    \unitlength=4pt
    \begin{picture}(25, 32)(0,-12)
    \gasset{Nw=5,Nh=5,Nmr=2.5,curvedepth=0}
    \thinlines
    \node[Nmarks=if,iangle=180,fangle=180](A0)(0,0){$0$}
    \node[Nmarks=f,fangle=270](A1)(10,10){$1$}
    \node(A2)(25,20){$2$}
    \node[Nmarks=f,fangle=0](A3)(25,0){$3$}
    \node(A4)(10,-10){$4$}
    \node[Nmarks=f,fangle=0](A5)(25,-10){$5$}
    \drawloop[loopangle=90](A1){$a$}
    \drawedge(A0,A1){$a$}
    \drawedge[ELside=r](A0,A4){$b$}
    \drawedge(A1,A2){$a$}
    \drawedge(A3,A1){$a$}
    \gasset{curvedepth=3}
    \drawedge(A2,A3){$b$}
    \drawedge(A3,A2){$a$}
    \drawedge(A4,A5){$a$}
    \drawedge(A5,A4){$b$}
    \end{picture}
  \end{center}
  \caption{Un automate non déterministe reconnaissant $L$.}
\end{figure}