%% 
%%  The LaTeX Graphics Companion, 2ed (first printing May 2007)
%% 
%%  Example 6-2-17 on page 342.
%% 
%%  Copyright (C) 2007 Michel Goossens, Frank Mittelbach, Denis Roegel, Sebastian Rahtz, Herbert Vo\ss 
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 

\documentclass{ttctexa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{159.83385pt}
\StartShownPreambleCommands
\usepackage{pstricks,pst-node}
\StopShownPreambleCommands
\begin{document}
\begin{pspicture}(2.75,3)
  \rput(1.5,2.8){\ovalnode{A}{root}}
  \rput[lb](0,0){\ovalnode{B}{1}}
  \rput[b](1.5,0){\ovalnode{C}{2}}
  \rput[rb](3,0){\ovalnode{D}{3}}
  \ncline{->}{A}{B}\ncline{->}{A}{C}\ncline{->}{A}{D}
\psset{linecolor=blue}
  \ncdiag[arm=0,angleA=80,angleB=-160]{<-}{B}{A}
  \ncdiag[arm=0,angleA=100,angleB=-20]{<-}{D}{A}
\end{pspicture}
\end{document}
