%% 
%%  Ein Beispiel der DANTE-Edition
%%  
%%  7. Auflage
%% 
%%  Beispiel 15-04-2 auf Seite 272.
%% 
%%  Copyright (C) 2016 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
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%% 
\documentclass[]{exaarticle}
\pagestyle{empty}
\setlength\textwidth{121.16928pt}
\setlength\parindent{0pt}
%StartShownPreambleCommands
\usepackage{pst-node}
%StopShownPreambleCommands
\begin{document}
\begin{pspicture}[showgrid](3,3)
 \rput[bl](0,0){\rnode{A}{Idea 1}}
 \rput[tr](3,3){\rnode{B}{Idea 2}}\psset{nodesep=3pt}
 \ncarc[arcangle=20]{->}{A}{B}\ncarc[arcangle=20]{->}{B}{A}
 \rput[lt](0,3){\rnode{A}{Idea 3}}
 \rput[rb](3,0){\rnode{B}{Idea 4}}
 \ncarc*{<->}{A}{B}\ncarc*{<->}{B}{A}
\end{pspicture}
\end{document}