2 papers
math.FA2018
Spectral sets and operator radii
Catalin Badea, Michel Crouzeix, Hubert Klaja
We study different operator radii of homomorphisms from an operator algebra into and show that these can be computed explicitly in terms of the usual norm. As an application…
math.FA2015
Rank one perturbations of diagonal operators without eigenvalues
Hubert Klaja
In this paper, we prove that every diagonal operator on a Hilbert space of which is of multiplicity one and has perfect spectrum admits a rank one perturbation without eigenvalues.…