English

Some $\mathbb{A}$-numerical radius inequalities for $d\times d$ operator matrices

Functional Analysis 2020-04-01 v1

Abstract

Let AA be a positive (semidefinite) bounded linear operator acting on a complex Hilbert space (H,)\big(\mathcal{H}, \langle \cdot\mid \cdot\rangle \big). The semi-inner product xyA:=Axy{\langle x\mid y\rangle}_A := \langle Ax\mid y\rangle, x,yHx, y\in\mathcal{H} induces a seminorm A{\|\cdot\|}_A on H\mathcal{H}. Let TT be an AA-bounded operator on H\mathcal{H}, the AA-numerical radius of TT is given by \begin{align*} \omega_A(T) = \sup\Big\{\big|{\langle Tx\mid x\rangle}_A\big|: \,\,x\in \mathcal{H}, \,{\|x\|}_A = 1\Big\}. \end{align*} In this paper, we establish several inequalities for ωA(T)\omega_\mathbb{A}(\mathbb{T}), where T=(Tij)\mathbb{T}=(T_{ij}) is a d×dd\times d operator matrix with TijT_{ij} are AA-bounded operators and A\mathbb{A} is the diagonal operator matrix whose each diagonal entry is AA.

Keywords

Cite

@article{arxiv.2003.14378,
  title  = {Some $\mathbb{A}$-numerical radius inequalities for $d\times d$ operator matrices},
  author = {Kais Feki},
  journal= {arXiv preprint arXiv:2003.14378},
  year   = {2020}
}
R2 v1 2026-06-23T14:34:11.424Z