%% The LaTeX Graphics Companion, 2ed (first printing May 2007)

%%
%% The LaTeX Graphics Companion, 2ed (first printing May 2007)
%%
%% Example 7-1-1 on page 468.
%%
%% 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]{xy}
\StopShownPreambleCommands
\begin{document}
\[
\xymatrix{
A & *+[F]{\sum_{i=n}^m {i^2}} \\
& {\bullet} & D \ar[ul]
}\]
\end{document}