Existence and multiplicity of solutions for resonant $(p,2)$-equations

Nikolaos S. Papageorgiou, Vicenţiu D. Rădulescu, Dušan D. Repovš

Published 2018-01-17Version 1

We consider Dirichlet elliptic equations driven by the sum of a $p$-Laplacian $(2<p)$ and a Laplacian. The conditions on the reaction term imply that the problem is resonant at both $\pm\infty$ and at zero. We prove an existence theorem (producing one nontrivial smooth solution) and a multiplicity theorem (producing five nontrivial smooth solutions, four of constant sign and the fifth nodal; the solutions are ordered). Our approach uses variational methods and critical groups.