Bull. Korean Math. Soc. 2014; 51(4): 1031-1040
Printed July 1, 2014
https://doi.org/10.4134/BKMS.2014.51.4.1031
Copyright © The Korean Mathematical Society.
Chunji Li, Muneo Ch\={o}, and Mi Ryeong Lee
Northeastern University, Kanagawa University, Catholic University of Daegu
In this paper, we show that any cubically hyponormal weighted shift with first two equal weights is flat. And we give an example of a weighted shift which is not cubically hyponormal but almost-cubically hyponormal.
Keywords: weighted shift, cubically hyponormal operator, flatness
MSC numbers: Primary 47B37; Secondary 47B20
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