Which 2-hyponormal 2-variable weighted shifts are subnormal?

Authors

• Raúl E. Curto, University of Iowa
• Sang Hoon Lee, Chungnam National University
• Jasang Yoon, The University of Texas Rio Grande ValleyFollow

Document Type

Article

Publication Date

10-16-2008

Abstract

It is well known that a 2-hyponormal unilateral weighted shift with two equal weights must be flat, and therefore subnormal. By contrast, a 2-hyponormal 2-variable weighted shift which is both horizontally flat and vertically flat need not be subnormal. In this paper we identify a large class S of flat 2-variable weighted shifts for which 2-hyponormality is equivalent to subnormality. One measure of the size of S is given by the fact that within S there are hyponormal shifts which are not subnormal.

Comments

© 2008 Elsevier Inc. All rights reserved.

http://www.elsevier.com/open-access/userlicense/1.0/

Recommended Citation

Curto, Raúl E., Sang Hoon Lee, and Jasang Yoon. "Which 2-hyponormal 2-variable weighted shifts are subnormal?." Linear algebra and its applications 429, no. 8-9 (2008): 2227-2238. https://doi.org/10.1016/j.laa.2008.06.017

First Page

2227

Last Page

2238

Publication Title

Linear Algebra and Its Applications

DOI

10.1016/j.laa.2008.06.017