The TeX below generates a diagram with minuscule arrow-heads. I've tried
\SelectTips, but that doesn't seem to make any difference.
What can I do about this to get sensible diagrams on slides, please?
\documentclass{slides}
\usepackage[all]{xy}
\begin{document}
\begin{slide}
Compare $\xymatrix{A \ar[r] & B}$ with $A\rightarrow B$.
\end{slide}
\end{document}