Quadratically hyponormal weighted shifts and their examples |
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Authors: | Il Bong Jung Sang Soo Park |
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Institution: | (1) Department of Mathematics College of Natural Sciences, Kyungpook National University, 702-701 Taegu, Korea |
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Abstract: | We discuss some characterizations for the quadratical hyponormal unilateral weighted shiftW
with a weight sequence , 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 : {ie480-1} which is a back step extension of subnormal completion ofu,v, andw with0, and prove that the recursively weighted shiftW
is quadratically hyponormal if and only if it is positively quadratically hyponormal.Research partially supported by KOSEF 971-0102-006-2 and the Basic Science Research Institute Program, Ministry of Education, 1997, BSRI-97-1401. |
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Keywords: | 47B37 47B20 |
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