# How to shrink arrow labels in xymatrix?

I know how to shrink a diagram changing the column or row spacing, but I don't know to do it for the arrow labels. I can shrink an entry by using the standard font size changing commands, like \small, \scriptstyle, etc. However this doesn't work for arrow labels. For example,

\documentclass[12pt, a4paper]{article}% a minimal example

\usepackage[all]{xy}
\xyoption{pdf}
\begin{document}
$\xymatrix{ \scriptstyle{X}\ar[d]^{F_0}_{\scriptstyle{F_0}}\\ Y }$
\end{document}


works for the entry X but not for the arrow label. Is there a way to shrink arrow labels in xymatrix?

The simplest way is to box the \xymatrix and to choose the font size in the box.

\documentclass[12pt, a4paper]{article}% a minimal example
\usepackage[all,cmtip]{xy}

\begin{document}

$\mbox{\xymatrix{ X\ar[d]^{F_0}_{F_0}\\ Y }} \quad \mbox{\small \xymatrix{ X\ar[d]^{F_0}_{F_0}\\ Y }% } \quad \mbox{\footnotesize \xymatrix{ X\ar[d]^{F_0}_{F_0}\\ Y }% } \quad \mbox{\scriptsize \xymatrix{ X\ar[d]^{F_0}_{F_0}\\ Y }% } \quad \mbox{\tiny \xymatrix{ X\ar[d]^{F_0}_{F_0}\\ Y }% }$

\end{document}


• I've been told that \scriptscriptstyle would work for arrow labels, if one wants to shrink arrow labels only, and it does. I tried \tiny, but it doesn't. I don't know why. – Quique Ruiz Feb 24 '17 at 4:01