[Xy-pic] diamond-shaped frames

[Maja Karaga]

Dear all,
I somehow got stuck with the problem of obtaining diamond-shaped frames
inside the \xymatrix command. For now, the only solution I've came up with
is following:

\usepackage[all]{xy}
\thispagestyle{empty}
\begin{document}
\newcommand{\match}{*=<3.4ex>[F-]{\txt{\scriptsize{$\hspace{1cm} $}}}}
\newcommand{\matchiii}{*=<3.4ex>[F-]{\txt{\scriptsize{$M_j$}}}}
\newcommmnd{\matchi}{*=<3.4ex>[F-]{\txt{\tiny{Begin}}}}
\newcommand{\matchii}{*=<3.4ex>[F-]{\txt{\tiny{End}}}}
\newcommand{\delete}{*=<4ex>[o][F-]{\txt{\scriptsize{$D_j$}}}}
\newcommand{\deletei}{*=<4ex>[o][F-]{\txt{\scriptsize{$\hspace{1cm} $}}}}
\newcommand{\inserti}{*=<3ex>[F:<5pt>]{\txt{\scriptsize{$I_j$}}}}
\newcommand{\insertii}{*=<3ex>[F:<5pt>]{\txt{\scriptsize{$\hspace{1cm}
$}}}}
\newcommand{\insertix}{*=-<1ex>[F]{\txt{$\hspace{2cm} $ \\
$\hspace{2cm}$}}}
\newcommand{\diame}{\rotatebox{45}{\frame{\rotatebox{315}{\txt{\scriptsize{$\hspace{0.65cm}$}}}}}}
\newcommand{\diamf}{\rotatebox{45}{\frame{\rotatebox{315}{\txt{\footnotesize{$I_j$}}}}}}
\xymatrix@!=1.7pc{ & \deletei \ar[d] \ar[r] \ar[ddr] & \delete \ar[d]
\ar[r] \ar[ddr] & \deletei \ar[d] \ar[ddr] & \\
          \diame &  \diame  & \diamf & \diame & & \\
          \matchi \ar[u] \ar[r] \ar[uur] & \match \ar[u] \ar[r] \ar[uur] &
\matchiii \ar[u] \ar[r] \ar[uur]& \match \ar[u]\ar[r]& \matchii \\
          }


which is not satisfactory from obvious reasons (for one, it works properly
only in .ps version, so please convert to .ps to see results.)
I would appreciate any help or suggestions.
Thanks,
Maja

M. Karaga,
Department of Mathematics,
University of Zagreb