English

Power bounded $m$-left invertible operators

Functional Analysis 2019-03-15 v2

Abstract

A Hilbert space operator S\BS\in\B is left mm-invertible by T\BT\in\B if j=0m(1)mj(mj)TjSj=0,\sum_{j=0}^m{(-1)^{m-j}\left(\begin{array}{clcr}m\\j\end{array}\right)T^jS^j}=0, SS is mm-isometric if j=0m(1)mj(mj)SjSj=0\sum_{j=0}^m{(-1)^{m-j}\left(\begin{array}{clcr}m\\j\end{array}\right){S^*}^jS^j}=0 and SS is (m,C)(m,C)-isometric for some conjugation CC of \H if j=0m(1)mj(mj)SjCSjC=0.\sum_{j=0}^m{(-1)^{m-j}\left(\begin{array}{clcr}m\\j\end{array}\right){S^*}^jCS^jC}=0. If a power bounded operator SS is left invertible by a power bounded operator TT, then SS (also, TT^*) is similar to an isometry. Translated to mm-isometric and (m,C)(m,C)-isometric operators SS this implies that SS is 11-isometric, equivalently isometric, and (respectively) (1,C)(1,C)-isometric.

Keywords

Cite

@article{arxiv.1903.03417,
  title  = {Power bounded $m$-left invertible operators},
  author = {B. P. Duggal and C. S. Kubrusly},
  journal= {arXiv preprint arXiv:1903.03417},
  year   = {2019}
}

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R2 v1 2026-06-23T08:02:12.666Z