# Use special objects of xy-pic with beamer

When I try to use the general format for labels (cf. xyguide, §2.2) together with beamer overlays, the part that should show up later isn't formatted properly. I guess, beamer doesn't convert the * properly. What can I do? See the code below.

\documentclass{beamer}

\mode<presentation>
{
\usecolortheme{seahorse}
\setbeamercovered{covered}
}

\usepackage{tikz}
\usepackage[all]{xy}

\begin{document}
\begin{frame}
$\xymatrix@=1.5em{ *++[o][F]{C} \only<+->{\ar@/^/[r]^{\alpha\rho}} & \uncover<.->{*++[o][F]{Z}} \only<.->{\ar@/^/[l]^{100\%}} }$
\end{frame}

\end{document}

-

It's caused by the \uncover and grouping of the following expression. Without it, it works - so perhaps omit uncovering piecewise, or make it differently. The syntax works:
\begin{frame}
$\xymatrix@=1.5em{ *++[o][F]{C} \only<+->{\ar@/^/[r]^{\alpha\rho}} & *++[o][F]{Z} \only<.->{\ar@/^/[l]^{100\%}} }$

I would use TikZ overlays instead. I guess, when the good old xypic package has been developed, beamer overlays didn't exist yet. If you would like to test it with TikZ, just extend your question to be open for a TikZ way, and we'll try.