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Integral Equations and Operator Theory

, Volume 36, Issue 4, pp 480–498 | Cite as

Quadratically hyponormal weighted shifts and their examples

  • Il Bong Jung
  • Sang Soo Park
Article

Abstract

We discuss some characterizations for the quadratical hyponormal unilateral weighted shiftWα with a weight sequence α, which give a distinction example for quadratical hyponormality and positively quadratical hyponormality. In addition, we consider a recursively quadratically hyponormal weighted shift with a recursive weight α: {ie480-1} which is a back step extension of subnormal completion ofu,v, andw with0<x<-u<v<w, and prove that the recursively weighted shiftWα is quadratically hyponormal if and only if it is positively quadratically hyponormal.

1991 Mathematics Subject Classification

47B37 47B20 

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Copyright information

© Birkhäuser Verlag 2000

Authors and Affiliations

  • Il Bong Jung
    • 1
  • Sang Soo Park
    • 1
  1. 1.Department of Mathematics College of Natural SciencesKyungpook National UniversityTaeguKorea

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