% !TEX TS-program = XeLaTeX
% Commands for running this example:
% 	 xelatex color-math2
% End of Commands
\documentclass{article}
\pagestyle{empty}
\usepackage{color,amscd,amsmath}
\usepackage[all]{	XY}
\usepackage{xepersian}
\settextfont{Persian Modern}
\xymatrix @1{
A& G \ar `ur^l[l]`^dr[l]_b [l]\\
B \ar`lu_u[u] `_ur[u] ^a [u]}

\end{displaymath}