Perturbed Browder, Weyl theorems and their variations: An addendum

Bhagwati Prashad Duggal, In Hyun Kim

Abstract


We generalize some results of Zariouh \cite{Za2} on properties $(\bf{Z}_{\Pi^a})$ and $(\bf{Z}_{E^a})$ from the direct sum $A\oplus B$ (of Banach space operators $A, B$) to upper triangular matrix operators with main diagonal $\{A, B\}$ and answer two questions from \cite{Za2}, one of them affirmatively and the other in the negative.


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References


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