%% 
%%  A DANTE-Edition example
%% 
%% 
%%  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{177.70511pt}
\setlength\parindent{0pt}

\usepackage{pstricks,pst-node}

\begin{document}
\psset{linestyle=solid}
$\psmatrix[mnode=circle,emnode=C,colsep=1cm]
     & X & \\
   Y & Z &
 \endpsmatrix
 \psset{nodesep=3pt,arrows=->}
 \ncline{1,2}{2,1} \ncline{1,2}{2,2}
 \ncline[linestyle=dotted]{2,1}{2,2}
 \ncline[linestyle=dashed,
   linecolor=red]{->}{2,2}{1,1}$
\end{document}
