An Algorithm for Quartically Hyponormal Weighted Shifts

- Journal title : Kyungpook mathematical journal
- Volume 51, Issue 2, 2011, pp.187-194
- Publisher : Department of Mathematics, Kyungpook National University
- DOI : 10.5666/KMJ.2011.51.2.187

Title & Authors

An Algorithm for Quartically Hyponormal Weighted Shifts

Baek, Seung-Hwan; Jung, Il-Bong; Moo, Gyung-Young;

Baek, Seung-Hwan; Jung, Il-Bong; Moo, Gyung-Young;

Abstract

Examples of a quartically hyponormal weighted shift which is not 3-hyponormal are discussed in this note. In [7] Exner-Jung-Park proved that if (x) : with 0 < x , then is quartically hyponormal but not 4-hyponormal. And, Curto-Lee([5]) improved their result such as that if : with 0 < x , then is quartically hyponormal but not 3-hyponormal. In this note, we improve slightly Curto-Lee's extremal value by using an algorithm and computer software tool.

Keywords

quartically hyponormal operators;cubically hyponormal operators;quadratically hyponormal operators;weighted shifts;

Language

English

Cited by

References

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