\documentclass{ppex}
\nonstopmode
\usepackage [all,poly]{xy}
\pagestyle{empty}
\setlength\textwidth{135.0pt}
\begin{document}
\ResetPreambleCommands
\ReadyForTheFray
\usepackage [all,poly]{xy}
\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}

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