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arXiv · 2002.02905

Some $A$-spectral radius inequalities for $A$-bounded Hilbert space operators

Kais Feki
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Abstract

Let $r_A(T)$ denote the $A$-spectral radius of an operator $T$ which is bounded with respect to the seminorm induced by a positive operator $A$ on a complex Hilbert space $\mathcal{H}$. In this paper, we aim to establish some $A$-spectral radius inequalities for products, sums and commutators of $A$-bounded operators. Moreover, under suitable conditions on $T$ and $A$ we show that \begin{equation*} r_A\left( \sum_{k=0}^{+\infty}c_{k}T^{k}\right) \leq \sum_{k=0}^{+\infty}|c_{k}|\left[r_A(T)\right]^{k}, \end{equation*} where $c_k$ are complex numbers for all $k\in \mathbb{N}$.

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Kais Feki. 2020-02-07. Some $A$-spectral radius inequalities for $A$-bounded Hilbert space operators. https://arxiv.org/abs/2002.02905

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