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$A$-Davis-Wielandt Radius Bounds of Semi-Hilbertian Space Operators

Functional Analysis 2024-08-01 v1

Abstract

Consider H\mathcal{H} is a complex Hilbert space and AA is a positive operator on H.\mathcal{H}. The mapping ,A:H×HC\langle\cdot,\cdot\rangle_A: \mathcal{H}\times \mathcal{H} \to \mathbb {C}, defined as y,zA=Ay,z\left\langle y,z\right\rangle_{A}=\left\langle Ay,z\right\rangle for all y,zy,z \in H{\mathcal{H}}, induces a seminorm A \left\Vert \cdot\right\Vert_{A}. The AA-Davis-Wielandt radius of an operator SS on H\mathcal{H} is defined as dωA(S)=sup{Sz,zA2+SzA4:zA=1}.d\omega_{A}\left( S\right) =\sup \left\{ \sqrt{\left\vert \left\langle Sz,z\right\rangle_{A}\right\vert ^{2}+\left\Vert Sz\right\Vert_{A}^{4}} :\left\Vert z\right\Vert_{A}=1\right\} \text{.} We investigate some new bounds for dωA(S)d\omega_{A}\left( S\right) which refine the existing bounds. We also give some bounds for the 2×22\times 2 off-diagonal block matrices.

Keywords

Cite

@article{arxiv.2407.21639,
  title  = {$A$-Davis-Wielandt Radius Bounds of Semi-Hilbertian Space Operators},
  author = {Messaoud Guesba and Somdatta Barik and Pintu Bhunia and Kallol Paul},
  journal= {arXiv preprint arXiv:2407.21639},
  year   = {2024}
}