Structure of the solution set for a vector valued elliptic boundary value problem with a Lipschitz nonlinear term

We consider the boundary value problem with the Dirichlet condition in a Banach space for a semilinear elliptic equation on a bounded domain in R-n whose nonlinear term satisfies the Lipschitz condition. If the Lipschitz constant L is less than lambda(l), then this problem has a unique solution, where lambda(l) is the least eigenvalue of the corresponding (real valued) eigenvalue problem. On the other hand, for any L > lambda(1) we can construct a nonlinear term with the Lipschitz constant L such that the solution set is homeomorphic to any prescribed closed subset of the Banach space. (c) 2005 Elsevier Ltd. All rights reserved.