Multiplicity Results for Nonlinear Nonhomogeneous Robin Problems with Indefinite Potential Term

We consider a nonlinear Robin problem driven by a general nonhomogeneous differential operator plus an indefinite potential term. The reaction is of generalized logistic type. Using variational tools we prove a multiplicity theorem producing three nontrivial solutions with sign information (positive, negative and nodal). In the particular case of ( p , 2)-equations, employing also critical groups, we produce a second nodal solution. Our results extend earlier multiplicity results for coercive problems.