%% 
%%  The LaTeX Graphics Companion, 2ed (first printing May 2007)
%% 
%%  Example 7-4-26 on page 497.
%% 
%%  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{159.83385pt}
\StartShownPreambleCommands
\usepackage[all,poly]{xy}
\StopShownPreambleCommands
\begin{document}
\newcounter{node}
%
\[
\renewcommand{\objectstyle}{\scriptstyle}
\newcommand{\Letter}%
    {{\setcounter{node}%
     {\xypolynode}\Alph{node}}}
%
\begin{xy} /r11mm/:
  (2,4.8), {\xypolygon6{~*{\xypolynode}}}
 ,(2,2.5), {*{0}*\cir<5pt>{}
               \xypolygon6{~*{\xybox{%
              *{\xypolynode}*\cir<2mm>{}}}}}
 ,(2,0)  ,  {\xypolygon6{%
                ~><{@/_.5ex/}
                ~>>{_{\delta^{\xypolynode}
                            _{\xypolynum}}}
                ~<<{@{=}}
                ~<>{|\uparrow}
                ~*{\Letter}}}
\end{xy}
\]
\end{document}