%0 Journal Article
%T On a class of optimal partition problems related to the Fu£¿\'£¿k spectrum and to the monotonicity formulae
%A Monica Conti
%A Susanna Terracini
%A Gianmaria Verzini
%J Mathematics
%D 2003
%I arXiv
%X In this paper we give an unified approach to some questions arising in different fields of nonlinear analysis, namely: (a) the study of the structure of the Fu\v{c}\'\i k spectrum and (b) possible variants and extensions of the monotonicity formula by Alt--Caffarelli--Friedman \cite{acf}. In the first part of the paper we present a class of optimal partition problems involving the first eigenvalue of the Laplace operator. Beside establishing the existence of the optimal partition, we develop a theory for the extremality conditions and the regularity of minimizers. As a first application of this approach, we give a new variational characterization of the first curve of the Fu\v{c}\'\i k spectrum for the Laplacian, promptly adapted to more general operators. In the second part we prove a monotonicity formula in the case of many subharmonic components and we give an extension to solutions of a class of reaction--diffusion equation, providing some Liouville--type theorems.
%U http://arxiv.org/abs/math/0312207v1