Vitaly Volpert, Vitali Vougalter Solvability in the sense of sequences for some non Fredholm operators (251K, pdf) ABSTRACT. We study solvability of certain linear nonhomogeneous elliptic problems and show that under reasonable technical conditions the convergence in L^2(R^d) of their right sides implies the existence and the convergence in H^2(R^d) of the solutions. The equations involve second order differential operators without Fredholm property and we use the methods of spectral and scattering theory for for Schroedinger type operators analogously to our preceding work.