Extremal solutions of [formula omitted]-Laplacian–diffusion scalar problems with nonlinear functional boundary conditions in a unified way

Abstract

The aim of this paper is to ensure the existence of extremal solutions lying between a pair of lower and upper solutions for a second-order differential equation that includes both the φ -Laplacian and some classes diffusion equations. The results hold from a suitable change of variables. An example is given to expose the applicability of the obtained results.