35 citations · 72 across the 13 of their papers we have counts for
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math.SP2014
Estimating the number of eigenvalues of linear operators on Banach spaces
Michael Demuth, Franz Hanauska, Marcel Hansmann +1
Let be a bounded operator on a Banach space, and consider a perturbation , where is compact. This work is concerned with obtaining bounds on the number of eigenv…
math.SP2014
An observation concerning boundary points of the numerical range
Marcel Hansmann
A theorem of Hübner states that non-round boundary points of the numerical range of a linear operator, i.e. points where the boundary has infinite curvature, are contained in the s…
math.SP2014
On non-round points of the boundary of the numerical range and an application to non-selfadjoint Schrödinger operators
Marcel Hansmann
We show that non-round boundary points of the numerical range of an unbounded operator (i.e. points where the boundary has infinite curvature) are contained in the spectrum of the…