%% 
%%  The LaTeX Graphics Companion, 2ed (first printing May 2007)
%% 
%%  Example 7-4-40 on page 506.
%% 
%%  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{207.83385pt}
\StartShownPreambleCommands
\usepackage[curve,knot,arrow,dvips]{xy}
\StopShownPreambleCommands
\begin{document}
\[\renewcommand{\labelstyle}{\scriptstyle}
\begin{xy} 0;/r8mm/:
 ,{\xcapv-|{a}}
 , +(0,1) ,{\xcaph|{b}\xunderh|{c}%
         \xcaph|{d}\xcapv|{e}}
 ,-(3,0),{\xoverh|{f}}
 ,+(1,0),{\xoverh|{g}}
 ,-(3,1),{\xcapv-|{h}\xcaph-|{i}}
 ,+(0,1),{\xunderh-|{j}}
 ,+(0,-1),{\xcaph-|{k}}
 ,+(0,1),{\xcapv|{l}}
\end{xy}\]
\end{document}