Isolated points of spectrum of k-quasi-*-class A operators

Salah Mecheri. "Isolated points of spectrum of k-quasi-*-class A operators." Studia Mathematica 208.1 (2012): 87-96. <http://eudml.org/doc/285572>.

@article{SalahMecheri2012,
abstract = {Let T be a bounded linear operator on a complex Hilbert space H. In this paper we introduce a new class, denoted *, of operators satisfying $T^\{*k\}(|T²|-|T*|²)T^\{k\} ≥ 0$ where k is a natural number, and we prove basic structural properties of these operators. Using these results, we also show that if E is the Riesz idempotent for a non-zero isolated point μ of the spectrum of T ∈ *, then E is self-adjoint and EH = ker(T-μ) = ker(T-μ)*. Some spectral properties are also presented.},
author = {Salah Mecheri},
journal = {Studia Mathematica},
keywords = {-paranormal operators; -class A operators; k-quasi--class A operators},
language = {eng},
number = {1},
pages = {87-96},
title = {Isolated points of spectrum of k-quasi-*-class A operators},
url = {http://eudml.org/doc/285572},
volume = {208},
year = {2012},
}

TY - JOUR
AU - Salah Mecheri
TI - Isolated points of spectrum of k-quasi-*-class A operators
JO - Studia Mathematica
PY - 2012
VL - 208
IS - 1
SP - 87
EP - 96
AB - Let T be a bounded linear operator on a complex Hilbert space H. In this paper we introduce a new class, denoted *, of operators satisfying $T^{*k}(|T²|-|T*|²)T^{k} ≥ 0$ where k is a natural number, and we prove basic structural properties of these operators. Using these results, we also show that if E is the Riesz idempotent for a non-zero isolated point μ of the spectrum of T ∈ *, then E is self-adjoint and EH = ker(T-μ) = ker(T-μ)*. Some spectral properties are also presented.
LA - eng
KW - -paranormal operators; -class A operators; k-quasi--class A operators
UR - http://eudml.org/doc/285572
ER -