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

%%
%% The LaTeX Graphics Companion, 2ed (first printing May 2007)
%%
%% Example 7-4-31 on page 500.
%%
%% 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,arc,dvips]{xy}
\StopShownPreambleCommands
\begin{document}
\[\begin{xy} /r12mm/:
(0,0)*@{*}="c",*++++!R{c}
,(1.2,.8)*+[][F]@{+}="p"
,*++!LD{p},"p";"c"**@{--}
,{\ellipse<>{}}
,{\ellipse(0.8){}}
,0;(-1,1)::
,{\ar@{.>} 0;(1,0)}
,{\ar@{.>} 0;(0,1)}
,"p";"c",{\ellipse(.8){--}}
,{\ellipse<3mm>{=}}
\end{xy}\]
\end{document}