Extremal Eigenvalues of the Laplacian on Euclidean domains and closed   surfaces
  We investigate properties of the sequences of extremal values that could be achieved by the eigenvalues of the Laplacian on Euclidean domains of unit volume, under Dirichlet and Neumann boundary conditions, respectively. In a second part, we study sequences of extremal eigenvalues of the Laplace-Beltrami operator on closed surfaces of unit area. 
Bruno Colbois, Ahmad El Soufi (LMPT)
math.MG