Wiener Estimates for Solutions of Elliptic Equations in Nondivergence Form

In this paper we deal with a Wiener estimate of the modulus of continuity at the boundary for the solutions of elliptic problems in nondivergence form. It is well known that the Wiener criterion for the continuity of the Laplace equation at a point of the boundary was given at first by Wiener (1923) and was extended to general linear elliptic (second order) equations in divergence form by Littman, Stampacchia, Weinberger (1963) (for the intermediate stages see the references of this last paper).