Vitali Vougalter, Vitaly Volpert Solvability relations for some diffusion equations with convection terms (126K, pdf) ABSTRACT. Linear second order elliptic equations containing the sum of the two Laplace operators with convection terms or a free Laplacian and a Laplacian with drift are considered in R^d. The corresponding operator L may be non Fredholm, such that solvability conditions for the equation Lu=f are unknown. We obtain solvability conditions in H^2(R^d) for the non self-adjoint problem via relating it to a self-adjoint Schroedinger type operator, for which solvability relations are derived in our preceding work.