\begin{figure}[H]
  \begin{center}
    \unitlength=4pt
    \begin{picture}(60, 30)(-10,-3)
    \gasset{Nw=5,Nh=5,Nmr=2.5,curvedepth=0}
    \thinlines
    \node[Nmarks=i,iangle=180](A1)(-10,17){$1$}
    \node(A2)(10,17){$2$}
    \node(A3)(0,0){$3$}
    \drawloop(A2){$b$}
    \drawedge(A1,A2){$a$}
    \drawedge(A2,A3){$b$}
    \drawedge(A3,A1){$a$}
    \node[Nmarks=f,fangle=90](A4)(30,17){$4$}
    \node[Nmarks=f,fangle=90](A5)(50,17){$5$}
    \drawedge(A2,A4){$a$}
    \gasset{curvedepth=-5}
    \drawedge(A3,A4){$a$}
    \gasset{curvedepth=5}
    \drawedge(A4,A5){$a$}
    \drawedge(A5,A4){$a$}
    \end{picture}
  \end{center}
  \caption{Un automate reconnaissant $L_1L_2$.}
\end{figure}