Perturbation Methods And Semilinear Elliptic Problems on Rn

The aim of this monograph is to discuss several elliptic problems on R n with two main features: they are variational and perturbative in nature, and standard tools of nonlinear analysis based on compactness arguments cannot be used in general. For these problems, a more specific approach that takes advantage of such a perturbative setting seems to be the most appropriate. The first part of the book is devoted to these abstract tools, which provide a unified frame for several applications, often considered different in nature. Such applications are discussed in the second part, and include semilinear elliptic problems on R n , bifurcation from the essential spectrum, the prescribed scalar curvature problem, nonlinear Schrödinger equations, and singularly perturbed elliptic problems in domains. These topics are presented in a systematic and unified way.