|
|||||
|
|
|
|
|
|
|
|
|
Hyponormality of
block Toeplitz operators
Caxing Gu, Jacob Hendricks and Daniel Rutherford |
|
Vol. 223 (2006), No. 1, 95–111
|
Abstract |
|
We show that for a block Toeplitz operator TG to be hyponormal, there is a matrix analogue of Cowen’s condition for a scalar hyponormal Toeplitz operator, but an additional condtion, G∗G = GG∗, is needed. A detailed analysis is given for the hypornormality of TG if G is a matrix trigomometric polynomial or G satisfies an extremal condition. Relevant results on kernels of block Hankel operators are also obtained. |
Keywords
Toeplitz operator, Hankel operator, hyponormal operator,
inner matrix
|
Mathematical Subject Classification 2000
Primary: 47B35, 47B20
|
Milestones
Received: 29 July 2003
Revised: 23 June 2005
Accepted: 23 June 2005
Published: 1 January 2006
|
Authors |
| Caxing Gu | |
| Department of Mathematics California Polytechnic State University San Luis Obispo, CA 93407 |
|
| Jacob Hendricks | |
| Department of Mathematical
Sciences University of Arkansas Fayetteville, AR 72701 |
|
| Daniel Rutherford | |
| Department of Mathematics University of California Davis, CA 95616 |
|
|
