  We study the quasi-long-range ordered phase of a 2D XY model with quenched
site-dilution using the spin-wave approximation and expansion in the parameter
which characterizes the deviation from completely homogeneous dilution. The
results, obtained by keeping the terms up to the third order in the expansion,
show good accordance with Monte Carlo data in a wide range of dilution
concentrations far enough from the percolation threshold. We discuss different
types of expansion.
