<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}
\UseTwocells
\[
\xymatrix @R=2.0pc @C=.8pc {
&amp; \bullet \ar @/^1ex/ [rr]
&amp;&amp; \bullet \ar @/^1ex/ [dr]
\\ \bullet \urtwocell&lt;2&gt; \rrtwocell&lt;2&gt;
           \drtwocell&lt;2&gt; \xtwocell[1,3]{}\omit
           \xtwocell[-1,3]{}\omit
&amp;&amp; \bullet \ar @/_1ex/ [ur]
           \ar @/^1ex/ [dr]
           \rrtwocell\omit
&amp;&amp; \bullet
\\ &amp; \bullet \ar @/_1ex/ [rr]
&amp;&amp;   \bullet \ar @/_1ex/ [ur]
}\]
\end{document}
</pre></body></html>