%% 
%%  The LaTeX Graphics Companion, 2ed (first printing May 2007)
%% 
%%  Example 7-4-37 on page 505.
%% 
%%  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{183.83385pt}
\StartShownPreambleCommands
\usepackage[all,poly,knot,dvips]{xy}
\StopShownPreambleCommands
\begin{document}
\[\UseTips
\renewcommand{\labelstyle}{\scriptstyle}
\begin{xy} 0;/r8mm/:
  (0,0)
 ,{\hover\hcross<><{1}|>|{2}>>>{3}%
    \hcross<><{4}|>|{5}>>>{6}\hover-}
 ,(0,-3)
 ,{\hover\htwistneg<><{1}|>|{2}>>>{3}%
   \htwistneg<><{4}|>|{5}>>>{6}\hover-}
\end{xy}\]
\end{document}