Startseite Mathematik Refinement of seminorm and numerical radius inequalities of semi-Hilbertian space operators
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Refinement of seminorm and numerical radius inequalities of semi-Hilbertian space operators

  • Pintu Bhunia , Raj Kumar Nayak und Kallol Paul EMAIL logo
Veröffentlicht/Copyright: 9. August 2022
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Abstract

Let 𝓗 be a complex Hilbert space and A be a non-zero positive bounded linear operator on 𝓗. The main aim of this paper is to discuss a general method to develop A-operator seminorm and A-numerical radius inequalities of semi-Hilbertian space operators using the existing corresponding inequalities of bounded linear operators on 𝓗. Among many other inequalities we prove that if S, T, X𝓑A(𝓗), i.e., if A-adjoint of S, T, X exist, then

2SAXTASSAX+XTTAA.

Further, we prove that if T𝓑A(𝓗), then

14TAT+TTAA18(T+TAA2+TTAA2)18(T+TAA2+TTAA2)+18cA2(T+TA)+18cA2(TTA)wA2(T).

Here wA(⋅), cA(⋅) and ∥⋅∥A denote A-numerical radius, A-Crawford number and A-operator seminorm, respectively.

  1. ( Communicated by Michal Zajac )

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Received: 2021-05-20
Accepted: 2021-08-16
Published Online: 2022-08-09
Published in Print: 2022-08-26

© 2022 Mathematical Institute Slovak Academy of Sciences

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