%% 
%%  A DANTE-Edition example
%% 
%%  Example 16-02-2 on page 228.
%% 
%%  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{129.70511pt}
\setlength\parindent{0pt}

\usepackage{pstricks,pst-node}

\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}\par\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}