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\documentclass{ppex} \nonstopmode \usepackage [all]{xy} \pagestyle{empty} \setlength\textwidth{207.0pt} \begin{document} \ResetPreambleCommands \ReadyForTheFray \usepackage [all]{xy} \[ \xymatrix{ A & *+[F]{\sum_{i=n}^m {i^2}} \\ & {\bullet} & D \ar[ul] }\] \end{document}