Positive solutions for nonlinear Robin problems

We consider a parametric Robin problem driven by the p-Laplacianwith an indefinite potential and with a superlinear reaction term which doesnot satisfy the Ambrosetti-Rabinowitz condition. We look for positive solutions. We prove a bifurcation-type theorem describing the nonexistence,existence and multiplicity of positive solutions as the parameter varies. Wealso show the existence of a minimal positive solution u_λ and establish themonotonicity and continuity of the map λ → u _λ.