A note on arithmetic-geometric-harmonic mean inequality of several positive operators
نویسندگان
1 Department of Mathematics, Faculty of science, University of Zanjan, Zanjan, Iran.
2 Department of Mathematics, Faculty of science, University of Zanjan, Zanjan, Iran
doi
10.30504/jims.2023.415016.1144چکیده
Suppose that $B_1,\cdots,B_m$ are positive operators on a Hilbert space $\mathcal{H}$. In this paper we generalize the weighted arithmetic, geometric and harmonic means as follows:\begin{align*}{\mathbf a_m}(\boldsymbol\kappa;\mathbf{B})&={\mathbf a_2}(k_1,N';B_1,{\mathbf a_{m-1}}(\boldsymbol\kappa';\mathbf{B}'))=\frac{k_1B_1+\cdots+k_mB_m}{N}\\{\mathbf h_m}(\boldsymbol\kappa;\mathbf{B})&={\mathbf h_2}(k_1,N';B_1,{\mathbf h_{m-1}}(\boldsymbol\kappa';\mathbf{B}'))=\left(\frac{k_1B_1^{-1}+\cdots+k_mB_m^{-1}}{N}\right)^{-1}\\{\mathbf g_m}(\boldsymbol\kappa;\mathbf{B})&={\mathbf g_2}(k_1,N';B_1,{\mathbf g_{m-1}}(\boldsymbol\kappa';\mathbf{B}'))\end{align*}where $\boldsymbol\kappa=(k_1,\cdots,k_m), N=k_1+\cdots+k_m, \boldsymbol\kappa'=(k_2,\cdots, k_m)$ and $N'=k_2+\cdots+k_m$. We show that the arithmetic-geometric-harmonic mean inequality holds. Also we investigate nine property of the geometric mean.