Infinitely many critical points of non-differentiable functions and applications to a Neumann-type problem involving the \(p\)-Laplacian (Q1614738)

The authors study the critical points for a family of functionals in a Banach space, which are possibly nonsmooth and depend also on a positive real parameter. Under an appropriate set of assumptions the existence of a sequence of critical points is shown. The paper adopts some techniques due to [\textit{B. Ricceri}, J. Comput. Appl. Math. 113, No. 1-2, 401-410 (2000; Zbl 0946.49001)]. Finally, two applications to the Neumann problem for an elliptic variational-hemivariational inequality with \(p\)-Laplacian are indicated.