Multiple positive solutions of four-point nonlinear boundary value problems for a higher-order pp-Laplacian operator with all derivatives

In this paper, we study the existence of multiple positive solutions for nonlinear four-point boundary value problems for a higher-order pp-Laplacian operator with all derivatives. Some new results are obtained for the multiplicity of positive solutions by applying the Avery–Henderson fixed point theorem and the Leggett–Williams fixed point theorem in a cone, which is different from the previous approaches.