Nodal sets and continuity of eigenfunctions of Krein-Feller operators on Riemannian manifolds
Let $d\geq1$, $Ω$ be a bounded domain of a smooth complete Riemannian d-manifold M, and $μ$ be a positive finite Borel measure with compact support in $\overlineΩ$. We prove the Courant nodal domain theorem for the eigenfunctions of Kreĭn-Feller operator $Δ_μ$ under the assumption that such eigenfunctions are continuous on $\overlineΩ$. For $d\geq2$, We prove that on a bounded domain $Ω\subset M$ with smooth boundary and on which the Green's function of the Laplace-Beltrami operator exists, the eigenfunctions of $Δ_μ$ are continuous on $Ω$. We also prove that if M is compact and $\partial M=\emptyset$, then the eigenfuctions of $Δ_μ$ are continuous on M.