We study a Dirichlet problem driven by the (degenerate or singular) fractional $p$-Laplacian and involving a $(p-1)$-superlinear reaction at infinity, not necessarily satisfying the Ambrosetti-Rabinowitz condition. Using critical point theory, truncation, and Morse theory, we prove the existence of at least three nontrivial solutions to the problem.
We consider a partial differential inclusion driven by the p-Laplacian and involving a nonsmooth potential, with Dirichlet boundary conditions. Under convenient assumptions on the behavior of the potential near the origin, the associated energy functional has a local linking. By means of nonsmooth Morse theory, we prove the existence of at least one or two nontrivial solutions, respectively, when the potential ...