Equality of essential spectra of quasisimilar subnormal operators

1990 ◽  
Vol 13 (3) ◽  
pp. 433-441 ◽  
Author(s):  
Liming Yang
2012 ◽  
Vol 74 (1) ◽  
pp. 7-24 ◽  
Author(s):  
Jiangang Qi ◽  
Shaozhu Chen

1997 ◽  
Vol 46 (3) ◽  
pp. 0-0 ◽  
Author(s):  
Nathan S. Feldman
Keyword(s):  

Author(s):  
Mircea Martin ◽  
Mihai Putinar
Keyword(s):  

1985 ◽  
Vol 31 (2) ◽  
pp. 161-169 ◽  
Author(s):  
Takayuki Furuta

At first we investigate the similarity between the Kleinecke-Shirokov theorem for subnormal operators and the Fuglede-Putnam theorem and also we show an asymptotic version of this similarity. These results generalize results of Ackermans, van Eijndhoven and Martens. Also we show two theorems on degree of approximation on subnormal derivation ranges. These results generalize results of Stampfli on degree of approximation on normal derivation ranges. The purpose of this paper is to show that the Fuglede-Putnam-type theorem on normal operators can certainly be generalized to subnormal operators.


1976 ◽  
Vol 82 (2) ◽  
pp. 259-262
Author(s):  
John B. Conway ◽  
Robert F. Olin

1977 ◽  
Vol 24 (1) ◽  
pp. 115-118
Author(s):  
Robert F. Olin
Keyword(s):  

1984 ◽  
Vol 25 (1) ◽  
pp. 99-101 ◽  
Author(s):  
Alan Lambert

In this note a characterization of subnormality of operators on Hilbert space is given. The characterization is in terms of a sequence of polynomials in the operator and its adjoint reminiscent of the binomial expansion in commutative algebras. As such no external Hilbert spaces are needed, nor is it necessary to introduce forms dependent on arbitrary sequences of vectors from the Hilbert space.


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