有人这么想吗?
\documentclass[a4paper,12pt]{article}
\usepackage[T1]{fontenc}
\usepackage{amssymb,amsfonts}
\usepackage[all,cmtip]{xy}
\begin{document}
\xymatrix@R=2pc@C=2pc{ A\ar[r]|{\setminus}& B \\
C \ar[r]|{\backslash} & D \\
E \ar[r]|{\object@{/}} & F \\
G \ar[r]|{\diagup}& H
}
\end{document}