2026/07/29 by Samuel Pérez-Ayala
Mathematics · #math.DG
arxiv created 2026/07/29 · arxiv updated 2026/07/31
We study the variational properties of the spectrum of the Dirichlet-to-Robin map Dg on connected compact manifolds with boundary of dimension at least three. For the first eigenvalue, we show that Type II Yamabe metrics extremize the first normalized eigenvalue functional, and we characterize all extremals. If [g] is a conformal class for which Dg has at least two negative eigenvalues, then we show the existence of a generalized metric that maximizes the second normalized eigenvalue of Dg in the conformal class. Moreover, we show that each such metric either defines a solution to an Escobar--Yamabe type equation on manifolds with boundary that changes sign along the boundary, or a weakly free-boundary harmonic map into the unit Euclidean ball.