On the boundary of the attainable set of the Dirichlet spectrum
arXiv:1112.4689 · doi:10.1007/s00033-012-0250-8
Abstract
Denoting by the set of the pairs for all the open sets with unit measure, and by the union of two disjoint balls of half measure, we give an elementary proof of the fact that $\partial\E$ has horizontal tangent at its lowest point .
arXiv comment7 pages, 3 figures