Glaeser's type gradient estimates for non-negative solutions of fully nonlinear elliptic equations

A Special Issue - Dedicated to Louis Nirenberg on the Occasion of his 85th Birthday. In this paper we discuss some extensions to a fully nonlinear setting of results by Y.Y. Li and L. Nirenberg about gradient estimates for nonnegative solutions of linear elliptic equations. Our approach relies heavily on methods developed by L. Caffarelli