Furtherance of numerical radius inequalities of Hilbert space operators

نویسندگان

چکیده

If A, B are bounded linear operators on a complex Hilbert space, then we prove that $$\begin{aligned} w(A)\le & {} \frac{1}{2}\left( \Vert A\Vert +\sqrt{r\left( |A||A^*|\right) }\right) ,\\ w(AB \pm BA)\le 2\sqrt{2}\Vert B\Vert \sqrt{ w^2(A)-\frac{c^2(\mathfrak {R}(A))+c^2(\mathfrak {I}(A))}{2} }, \end{aligned}$$ where $$w(\cdot ),\left\| \cdot \right\| $$ , and $$r(\cdot )$$ the numerical radius, operator norm, Crawford number, spectral radius respectively, $$\mathfrak {R}(A)$$ {I}(A)$$ real part, imaginary part of A respectively. The inequalities obtained here generalize improve existing well known inequalities.

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ژورنال

عنوان ژورنال: Archiv der Mathematik

سال: 2021

ISSN: ['0003-889X', '1420-8938']

DOI: https://doi.org/10.1007/s00013-021-01641-w