<html><head><meta name="color-scheme" content="light dark"></head><body><pre style="word-wrap: break-word; white-space: pre-wrap;">%% 
%%  The LaTeX Graphics Companion, 2ed (first printing May 2007)
%% 
%%  Example 7-4-22 on page 494.
%% 
%%  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[all,2cell]{xy}
\StopShownPreambleCommands
\begin{document}
\UseAllTwocells
\[
\renewcommand{\objectstyle}{\scriptstyle}
\renewcommand{\labelstyle}{\scriptstyle}
\xymatrix @=1pc {
&amp;&amp; \bullet \ar[2,2]
\\ \\
   \bullet \ar[-2,2]
        \rrtwocell {=}
        \xtwocell[0,4]{}\omit{^&lt;-4&gt;a}
&amp;&amp;  x_b \ar[rr] \ar[dr]_{\mathrm{id}_x}
        \rrtwocell\omit{&lt;1.5&gt;}
&amp;&amp; \bullet
\\ &amp;&amp;&amp; x_e \ar[ur]
}\]
\end{document}
</pre></body></html>