% mit dot2tex erzeugt. Aber die Abstände zwischen den Nodes sind viel zu groß.
\begin{tikzpicture}[>=latex',line join=bevel]
%%
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  \node (8) at (531bp,234bp) [draw,draw=none] {8};
  \node (11) at (531bp,90bp) [draw,draw=none] {11};
  \node (10) at (387bp,162bp) [draw,draw=none] {10};
  \node (13) at (603bp,90bp) [draw,draw=none] {13};
  \node (12) at (387bp,234bp) [draw,draw=none] {12};
  \node (15) at (99bp,162bp) [draw,draw=none] {15};
  \node (14) at (459bp,162bp) [draw,draw=none] {14};
  \node (17) at (675bp,90bp) [draw,draw=none] {17};
  \node (16) at (531bp,306bp) [draw,draw=none] {16};
  \node (19) at (747bp,90bp) [draw,draw=none] {19};
  \node (18) at (135bp,234bp) [draw,draw=none] {18};
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  \definecolor{strokecolor}{rgb}{0.53,0.53,0.53};
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  \definecolor{strokecolor}{rgb}{0.53,0.53,0.53};
  \draw [strokecolor,->] (2) ..controls (428.84bp,105.7bp) and (425.88bp,106.93bp)  .. (423bp,108bp) .. controls (364.03bp,129.82bp) and (342.86bp,121.96bp)  .. (6);
  \definecolor{strokecolor}{rgb}{0.53,0.53,0.53};
  \draw [strokecolor,->] (5) ..controls (254.14bp,105.09bp) and (194.39bp,121.26bp)  .. (15);
  \definecolor{strokecolor}{rgb}{0.53,0.53,0.53};
  \draw [strokecolor,->] (1) ..controls (440.35bp,36.129bp) and (281.29bp,67.941bp)  .. (3);
%
\end{tikzpicture}
