2021/07/07 by Hassannezhad, Asma, Sher, David · 1 citation
#58C40 (Secondary) #58J40 #58J50 (Primary) 35P15 #Analysis of PDEs (math.AP) #FOS: Mathematics #Spectral Theory (math.SP)
paper · doi:10.48550/arxiv.2107.03370
We consider Dirichlet-to-Neumann operators associated to Δ+q on a Lipschitz domain in a smooth manifold, where q is an L∞ potential. We prove a Courant-type bound for the nodal count of the extensions uk of the kth Dirichlet-to-Neumann eigenfunctions ϕk to the interior satisfying (Δ+q)uk=0. The classical Courant nodal domain theorem is known to hold for Steklov eigenfunctions, which are the harmonic extension of the Dirichlet-to-Neumann eigenfunctions associated to Δ. Our result extends it to a larger family of Dirichlet-to-Neumann operators. Our proof makes use of the duality between the Steklov and Robin problems.