scholarly journals Asymmetric Putnam-Fuglede Theorem for (n,k)-Quasi-∗-Paranormal Operators

Symmetry ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 64
Author(s):  
Ahmed Bachir ◽  
Abdelkader Segres

T ∈ B ( H ) is said to be ( n , k ) -quasi-∗-paranormal operator if, for non-negative integers k and n, ∥ T ∗ ( T k x ) ∥ ( 1 + n ) ≤ ∥ T ( 1 + n ) ( T k x ) ∥ ∥ T k x ∥ n ; for all x ∈ H . In this paper, the asymmetric Putnam-Fuglede theorem for the pair ( A , B ) of power-bounded operators is proved when (i) A and B ∗ are n-∗-paranormal operators (ii) A is a ( n , k ) -quasi-∗-paranormal operator with reduced kernel and B ∗ is n-∗-paranormal operator. The class of ( n , k ) -quasi-∗-paranormal operators properly contains the classes of n-∗-paranormal operators, ( 1 , k ) -quasi-∗-paranormal operators and k-quasi-∗-class A operators. As a consequence, it is showed that if T is a completely non-normal ( n , k ) -quasi-∗-paranormal operator for k = 0 , 1 such that the defect operator D T is Hilbert-Schmidt class, then T ∈ C 10 .

1991 ◽  
Vol 34 (1) ◽  
pp. 105-108
Author(s):  
James H. Olsen

AbstractIn this note we observe two consequences of Brunei's recent theorem. If T1,..., Tn are majorized by positive power-bounded operators S1,..., Sn of Lp, 1 < p < ∞, for which the ergodic theorem holds, then a multiple sequence ergodic theorem holds for T1,....,Tn. Further, the individual convergence for each Tk can be taken along uniform sequences.


2004 ◽  
Vol 70 (02) ◽  
pp. 463-478 ◽  
Author(s):  
N. KALTON ◽  
S. MONTGOMERY-SMITH ◽  
K. OLESZKIEWICZ ◽  
Y. TOMILOV

2016 ◽  
Vol 285 (1-2) ◽  
pp. 143-158 ◽  
Author(s):  
A. F. M. ter Elst ◽  
V. Müller

2010 ◽  
Vol 196 (3) ◽  
pp. 265-288 ◽  
Author(s):  
Markus Haase ◽  
Yuri Tomilov

2014 ◽  
Vol 224 (1) ◽  
pp. 25-45
Author(s):  
Angela A. Albanese ◽  
José Bonet ◽  
Werner J. Ricker

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