English

Aluthge transforms of weighted shifts on directed trees

Functional Analysis 2014-01-20 v1

Abstract

Aluthge transform of a bounded operator is generalized to the case of unbounded one. A formula for the Aluthge transform of a weighted shift on a directed tree is established and it is used to construct an example of a hyponormal operator whose Aluthge transform has trivial domain. It is proven that such an example can be also constructed in the class of composition operators. It is also shown that Aluthge transform of a closed, densely defined operator is not necessarily closable.

Keywords

Cite

@article{arxiv.1401.4415,
  title  = {Aluthge transforms of weighted shifts on directed trees},
  author = {Jacek Trepkowski},
  journal= {arXiv preprint arXiv:1401.4415},
  year   = {2014}
}

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15 pages