<html><head><meta name="color-scheme" content="light dark"></head><body><pre style="word-wrap: break-word; white-space: pre-wrap;">\documentclass{ppex}
\nonstopmode
\usepackage [all,2cell]{xy}
\pagestyle{empty}
\setlength\textwidth{183.0pt}
\begin{document}
\ResetPreambleCommands
\ReadyForTheFray
\usepackage [all,2cell]{xy}
\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>