<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,web]{xy}
\pagestyle{empty}
\setlength\textwidth{183.0pt}
\begin{document}
\ResetPreambleCommands
\ReadyForTheFray
\usepackage [all,web]{xy}
\[\renewcommand{\latticebody}{\drop@{o}}
\begin{xy}
 *\xybox{0;&lt;5mm,2mm&gt;:&lt;2mm,5mm&gt;::
 ,0,{\xylattice{-3}{3}{-3}{3}}}="S"
 ,{"S"+L \ar "S"+R*+!L{z_1}}
 ,{"S"+D \ar "S"+U*+!D{z_2}}
\end{xy}\]

\end{document}
</pre></body></html>