%% 
%%  Ein Beispiel der DANTE-Edition
%%  
%%  7. Auflage
%% 
%%  Beispiel 15-02-10 auf Seite 257.
%% 
%%  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{97.16928pt}
\setlength\parindent{0pt}
%StartShownPreambleCommands
\usepackage{pst-node}
%StopShownPreambleCommands
\begin{document}
\Cnode[radius=.3cm](.25,0){A}\Cnode[radius=.3cm](2.5,0){B}%
\ncbar[angle=90]{->}{A}{B}\ncbar[angle=-90,arm=.2cm]{->}{B}{A}

\vspace{1cm}
\Cnode[radius=.3cm](.25,0){A}\Cnode[radius=.3cm](2.5,0){B}
\psset{linearc=.2cm}\ncdiag[angle=90]{->}{A}{B}%
\ncdiag[angle=-90,armA=.2cm,armB=.75cm]{->}{B}{A}
\end{document}
