Existence and multiplicity of periodic solutions and subharmonic solutions for a class of elliptic equations

This paper focuses on the following elliptic equation { − Ű − p(x)u = f(x, u), a.e. x ∈ [0, l], u(0) − u(l) = ú(0) − ú(l) = 0, where the primitive function of f(x, u) is either superquadratic or asymptotically quadratic as |u| → ∞ or subquadratic as |u| → 0. By using variational method, e.g. the local linking theorem, fountain theorem, and the generalized mountain pass theorem, we establish the existence and multiplicity results for the periodic solution and subharmonic solution. rights reserved.