A Class of Norm Inequalities for Operator Monotone Functions and Hyponormal Operators

Complex Analysis and Operator Theory - Tập 18 - Trang 1-12 - 2024
Katarina Bogdanović1
1Department of Mathematics, University of Belgrade, Belgrade, Serbia

Tóm tắt

Let $$\Psi $$ , $$\Phi $$ be s.n. functions, $$p\ge 2,$$ and let $$\varphi $$ be an operator monotone function on $$[0,\infty )$$ such that $$\varphi (0)=0.$$ If are such that A and B are strictly accretive and then also and $$\begin{aligned}{} & {} \vert {\;\!\!\vert {AX\varphi {(B)}-\varphi {(A)}XB}\vert \;\!\!}\vert _\Psi \\{} & {} \qquad \le \left\| \,\!\sqrt{\varphi \Bigl ({\tfrac{A+A^*}{2}}\Bigr )-\tfrac{A+A^*}{2}\varphi ^\prime \Bigl ({\tfrac{A+A^*}{2}}\Bigr )} \Bigl ({\tfrac{A+A^*}{2}}\Bigr )^{-1}\!A(AX-XB)B\Bigl ({\tfrac{B+B^*}{2}}\Bigr )^{-1}\!\!\right. \\{} & {} \qquad \quad \left. \sqrt{\varphi \Bigl ({\tfrac{B+B^*}{2}}\Bigr )-\tfrac{B+B^*}{2}\varphi ^\prime \Bigl ({\tfrac{B+B^*}{2}}\Bigr )}\,\right\| _\Psi \,\!\!. \end{aligned}$$ under any of the following conditions: Alternative inequalities for $$\vert {\;\!\!\vert {\cdot }\vert \;\!\!}\vert _{\Phi ^{(p)}}$$ norms are also obtained.

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