فهرست مقالات positive operator

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  1 - Some improvements of numerical radius inequalities via Specht’s ratio
  Y. Khatib M. Hassani
  We obtain some inequalities related to the powers of numericalradius inequalities of Hilbert space operators. Some results thatemploy the Hermite-Hadamard inequality for vectors in normed linearspaces are also obtained. We improve and generalize someinequalities with re چکیده کامل

  We obtain some inequalities related to the powers of numericalradius inequalities of Hilbert space operators. Some results thatemploy the Hermite-Hadamard inequality for vectors in normed linearspaces are also obtained. We improve and generalize someinequalities with respect to Specht's ratio. Among them, we showthat, if $A, B\in \mathcal{B(\mathcal{H})}$ satisfy in someconditions, it follows that \begin{equation*} \omega^2(A^*B)\leq \frac{1}{2S(\sqrt{h})}\Big\||A|^{4}+|B|^{4}\Big\|-\displaystyle{\inf_{\|x\|=1}} \frac{1}{4S(\sqrt{h})}\big(\big\langle \big(A^*A-B^*B\big) x,x\big\rangle\big)^2 \end{equation*} for some $h>0$, where $\|\cdot\|,\,\,\,\omega(\cdot)$ and $S(\cdot)$denote the usual operator norm, numerical radius and the Specht'sratio, respectively. پرونده مقاله
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  2 - Advanced Refinements of Numerical Radius Inequalities
  Farzaneh Pouladi Najafabadi Hamid Moradi
  10.30495/ijm2c.2021.684828
  By taking into account that the computation of the numerical radius is an optimization problem, we prove, in this paper, several refinements of the numerical radius inequalities for Hilbert space operators. It is shown, among other inequalities, that if A is a bounded l چکیده کامل

  By taking into account that the computation of the numerical radius is an optimization problem, we prove, in this paper, several refinements of the numerical radius inequalities for Hilbert space operators. It is shown, among other inequalities, that if A is a bounded linear operator on a complex Hilbert space, thenω(A)≤½√(|| |A|2+|A*|2||+|| |A| |A*|+|A*| |A| ||),where ω(A), ||A||, and |A| are the numerical radius, the usual operator norm, and the absolute value of A, respectively. This inequality provides a refinement of an earlier numerical radius inequality due to Kittaneh, namely,ω(A)≤½(||A||+||A2||)½.Some related inequalities are also discussed. پرونده مقاله