Generalized spectrum of second order differential operators

Tomáš Gergelits, Bjørn Fredrik Nielsen, Zdeněk Strakoš

We analyze the spectrum of the operator ${\Delta }^{-1}[\nabla \cdot (K\nabla u)]$, where $\Delta$ denotes the Laplacian and $K=K(x,y)$ is a symmetric tensor. Our main result shows that this s…