Messirdi, Bekkai; Kouider, Miloud Hocine; Benharrat, Mohammed
(International Journal of Analysis and Applications, 2019-01-06)
When A∈ B (H) and B∈ B (K) are given, we denote by MC the operator on the Hilbert space H⊕ K of the form MC=(AC 0 B). In this paper we investigate the quasi-nilpotent part and the analytical core for the upper triangular ...