\begin{figure}[H]
  \begin{center}
    \unitlength=4pt
    \begin{picture}(30, 36)(-15,-2)
    \gasset{Nw=5,Nh=5,Nmr=2.5,curvedepth=0}
    \thinlines
    \node[Nmarks=i,iangle=180](A1)(-15,26){$1$}
    \node[Nmarks=f,fangle=0](A2)(15,26){$2$}
    \node[Nmarks=f,fangle=270](A3)(0,0){$3$}
    \drawedge(A2,A1){$a+b$}
    \drawedge[ELside=r](A2,A3){$b$}
    \drawedge[ELside=r](A3,A1){$a$}
    \gasset{curvedepth=7}
    \drawedge(A1,A2){$a^*b+a$}
    \gasset{curvedepth=-7}
    \drawedge[ELside=r](A1,A3){$b^*$}
    \drawedge[ELside=r](A3,A2){$a$}
    \end{picture}
  \end{center}
  \caption{Un automate étendu.}
\end{figure}