V.Baladi , L.-S.Young 
On the spectra of randomly perturbed expanding maps 
(145K, AmS TeX Version 2.1 (Postscript figure))

ABSTRACT.  We consider small random perturbations of expanding 
and piecewise expanding maps and prove the robustness 
of their invariant densities and rates of mixing.
We do this by proving the robustness of the spectra of their 
Perron-Frobenius operators.