Multiple positive solutions for semilinear Dirichlet problems with sign-changing weight function in infinite strip domains

In this paper, existence and multiplicity results to the following Dirichlet problem −∆u + u = λf (x)|u|q−1 + h(x)|u|p−1 , u > 0, u = 0, in Ω in Ω on ∂ Ω are established, where Ω = Ω × R, Ω ⊂ RN −1 is bounded smooth domain and N ≥ 2. Here 1 < q < 2 < p < 2∗ 2∗ = N2N2 if N ≥ 3, 2∗ = ∞ if N = 2 , λ is a positive real − parameter, the function f , among other conditions, can possibly change sign in Ω , and the function h satisfies suitable conditions. The study is based on the comparison of energy levels on Nehari manifold