%% 
%%  Ein Beispiel der DANTE-Edition
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%%  7. Auflage
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%%  Beispiel 15-02-2 auf Seite 254.
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%%  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{145.16928pt}
\setlength\parindent{0pt}
%StartShownPreambleCommands
\usepackage{pst-node}
%StopShownPreambleCommands
\begin{document}
\Cnode(0.5,0){A}\rput(0.5,0){\Large a}
\Cnode(2.5,0){B}\rput(2.5,0){\Large B} \ncline{A}{B}

\vspace{1cm}
\Cnode[radius=0.5cm](0.5,0){A}\rput(0.5,0){\Large a}%
\Cnode[radius=0.5cm](2.5,0){B}\rput(2.5,0){\Large B}
\ncline{A}{B}
\end{document}