Existence of minimizers for spectral problems
Dario Mazzoleni, Aldo M. Pratelli · arXiv (Cornell University) · 2011
In this paper we show that any increasing functional of the first k eigenvalues of the Dirichlet Laplacian admits a (quasi-)open minimizer among the subsets of R^N of unit measure. In particular, there exists such a minimizer which is bounded, where the bound depends on k and N, but not on the functional. In the meantime, we show that the ratio λ_k(Ω)/λ_1(Ω) is uniformly bounded for sets Ω\in R^N.