%% 
%%  A DANTE-Edition example
%% 
%%  Example 16-10-2 on page 264.
%% 
%%  Copyright (C) 2011 Herbert Voss
%% 
%%  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.
%% 
%% 
%% ==== 
% Show page(s) 1
%% 
\documentclass[]{article}
\pagestyle{empty}
\setlength\textwidth{375.57637pt}
\setlength\parindent{0pt}

\usepackage{pstricks,pst-node}

\begin{document}
\begin{pspicture}(10,5)
  \pnode(0,3){V}
  \cnode(1.5,3){0.25cm}{K1}
  \fnode[framesize=1.5cm](4,3){G1}\rput(4,3){\Large $G_1$}
  \fnode[framesize=1.5cm](4,1){G2}\rput(4,1){\Large $G_2$}
  \cnode*(6.5,3){0.1cm}{K2}
  \pnode(8,3){X}
  \psset{linewidth=1.5pt,arrows=->}
  \ncline{V}{K1}\naput{\Large V}
  \ncline{K1}{G1}
  \ncline{G1}{X}\naput[npos=0.75]{\Large X}
  \ncangle[angleA=-90,angleB=0]{K2}{G2}
  \ncangle[angleA=180,angleB=-90]{G2}{K1}
  \nbput[npos=2.5]{\textbf{\Large -}}
\end{pspicture}
\end{document}
