%% 
%%  The LaTeX Graphics Companion, 2ed (first printing May 2007)
%% 
%%  Example 6-2-59 on page 359.
%% 
%%  Copyright (C) 2007 Michel Goossens, Frank Mittelbach, Denis Roegel, Sebastian Rahtz, Herbert Vo\ss 
%% 
%%  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.
%% 

\documentclass{ttctexa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{159.83385pt}
\setlength\parindent{0pt}
\StartShownPreambleCommands
\usepackage{pstricks,pst-node}
\StopShownPreambleCommands
\begin{document}
\[
  \setlength\arraycolsep{1.1cm}
  \begin{array}{cc}
    \Rnode{a}{(X-A)} & \Rnode{b}{A} \\[1.5cm]
        \Rnode{c}{x} & \Rnode{d}{\tilde{X}}
  \end{array}
  \psset{nodesep=5pt,arrows=->}
  \everypsbox{\scriptstyle}
  \ncline{a}{c} \tlput{r}
  \ncline{a}{b} \taput{u}
  \ncline[linestyle=dashed]{c}{d} \tbput{b}
  \ncline{b}{d} \trput{s}
\]
\end{document}