On Lipschitz Perturbations of a Self-Adjoint Strongly Positive Operator

In this paper we study semilinear equations of the form Au + lambda F(u) = f, where A is a linear self-adjoint operator, satisfying a strong positivity condition, and F is a nonlinear Lipschitz operator. As applications we develop Krasnoselskii and Ky Fan type approximation results for certain pair of maps and to illustrate the usability of the obtained results, the existence of solution of an integral equation is provided.