2008/10/10 by Gesztesy, Fritz, Malamud, Mark M. · 1 citation
#35J40 #35P20 #47A10 #47F05 #Analysis of PDEs (math.AP) #FOS: Mathematics #Spectral Theory (math.SP)
paper · doi:10.48550/arxiv.0810.1789
We consider various closed (and self-adjoint) extensions of elliptic differential expressions of the type \cA=∑0≤ |α|,|β|≤ m(-1)αDαaα, β(x)Dβ, aα, β(⋅)∈ C∞(Ω), on smooth (bounded or unbounded) domains in \bbRn with compact boundary. Using the concept of boundary triples and operator-valued Weyl-Titchmarsh functions, we prove various trace ideal properties of powers of resolvent differences of these closed realizations of \cA and derive estimates on eigenvalues of certain self-adjoint realizations in spectral gaps of the Dirichlet realization. Our results extend classical theorems due to Visik, Povzner, Birman, and Grubb.