We provide a number of sharp inequalities involving the usual operator norms of Hilbert space operators and powers of the numerical radii. Based on the traditional convexity inequalities for nonnegative real numbers and some generalize earlier numerical radius inequalities, operator. Precisely, we prove that if $ {\bf A}_i, {\bf B}_i, {\bf X}_i\in \mathcal{B}(\mathcal{H}) $ ($ i = 1, 2, \cdots, n $), $ m\in \mathbb N $, $ p, q > 1 $ with $ \frac{1}{p}+\frac{1}{q} = 1 $ and $ \phi $ and $ \psi $ are non-negative functions on $ [0, \infty) $ which are continuous such that $ \phi(t)\psi(t) = t $ for all $ t \in [0, \infty) $, then
$ \begin{equation*} w^{2r}\left({\sum\limits_{i = 1}^{n} {\bf X}_i {\bf A}_i^m {\bf B}_i}\right)\leq \frac{n^{2r-1}}{m}\sum\limits_{j = 1}^{m}\left\Vert{\sum\limits_{i = 1}^{n}\frac{1}{p}S_{i, j}^{pr}+\frac{1}{q}T_{i, j}^{qr}}\right\Vert-r_0\inf\limits_{\left\Vert{\xi}\right\Vert = 1}\rho(\xi), \end{equation*} $
where $ r_0 = \min\{\frac{1}{p}, \frac{1}{q}\} $, $ S_{i, j} = {\bf X}_i\phi^2\left({\left\vert{ {\bf A}_i^{j*}}\right\vert}\right) {\bf X}_i^* $, $ T_{i, j} = \left({ {\bf A}_i^{m-j} {\bf B}_i}\right)^*\psi^2\left({\left\vert{ {\bf A}_i^j}\right\vert}\right) {\bf A}_i^{m-j} {\bf B}_i $ and
$ \rho(\xi) = \frac{n^{2r-1}}{m}\sum\limits_{j = 1}^{m}\sum\limits_{i = 1}^{n}\left({\left<{S_{i, j}^r\xi, \xi}\right>^{\frac{p}{2}}-\left<{T_{i, j}^r\xi, \xi}\right>^{\frac{q}{2}}}\right)^2. $
Citation: Mohammad H. M. Rashid, Feras Bani-Ahmad. An estimate for the numerical radius of the Hilbert space operators and a numerical radius inequality[J]. AIMS Mathematics, 2023, 8(11): 26384-26405. doi: 10.3934/math.20231347
We provide a number of sharp inequalities involving the usual operator norms of Hilbert space operators and powers of the numerical radii. Based on the traditional convexity inequalities for nonnegative real numbers and some generalize earlier numerical radius inequalities, operator. Precisely, we prove that if $ {\bf A}_i, {\bf B}_i, {\bf X}_i\in \mathcal{B}(\mathcal{H}) $ ($ i = 1, 2, \cdots, n $), $ m\in \mathbb N $, $ p, q > 1 $ with $ \frac{1}{p}+\frac{1}{q} = 1 $ and $ \phi $ and $ \psi $ are non-negative functions on $ [0, \infty) $ which are continuous such that $ \phi(t)\psi(t) = t $ for all $ t \in [0, \infty) $, then
$ \begin{equation*} w^{2r}\left({\sum\limits_{i = 1}^{n} {\bf X}_i {\bf A}_i^m {\bf B}_i}\right)\leq \frac{n^{2r-1}}{m}\sum\limits_{j = 1}^{m}\left\Vert{\sum\limits_{i = 1}^{n}\frac{1}{p}S_{i, j}^{pr}+\frac{1}{q}T_{i, j}^{qr}}\right\Vert-r_0\inf\limits_{\left\Vert{\xi}\right\Vert = 1}\rho(\xi), \end{equation*} $
where $ r_0 = \min\{\frac{1}{p}, \frac{1}{q}\} $, $ S_{i, j} = {\bf X}_i\phi^2\left({\left\vert{ {\bf A}_i^{j*}}\right\vert}\right) {\bf X}_i^* $, $ T_{i, j} = \left({ {\bf A}_i^{m-j} {\bf B}_i}\right)^*\psi^2\left({\left\vert{ {\bf A}_i^j}\right\vert}\right) {\bf A}_i^{m-j} {\bf B}_i $ and
$ \rho(\xi) = \frac{n^{2r-1}}{m}\sum\limits_{j = 1}^{m}\sum\limits_{i = 1}^{n}\left({\left<{S_{i, j}^r\xi, \xi}\right>^{\frac{p}{2}}-\left<{T_{i, j}^r\xi, \xi}\right>^{\frac{q}{2}}}\right)^2. $
[1] | S. Abramovich, G. Jameson, G. Sinnamon, Refining Jensen's inequality, Bull. Math. Soc. Sci. Math. Roumanie, 47 (2004), 3–14. |
[2] | J. S. Aujla, F. C. Silva, Weak majorization inequalities and convex functions, Linear Algebra Appl., 369 (2003), 217–233. https://doi.org/10.1016/S0024-3795(02)00720-6 doi: 10.1016/S0024-3795(02)00720-6 |
[3] | M. A. Dolat, K. A. Zoubi, Numerical radius inequalities for Hilbert space operators, J. Math. Ineq., 10 (2016), 1041–1049. http://dx.doi.org/10.7153/jmi-10-83 doi: 10.7153/jmi-10-83 |
[4] | S. S. Dragomir, Some inequalities for the Euclidean operator radius of two operators in Hilbert spaces, Linear Algebra Appl., 419 (2006), 256–264. https://doi.org/10.1016/j.laa.2006.04.017 doi: 10.1016/j.laa.2006.04.017 |
[5] | S. S. Dragomir, Reverse inequalities for the numerical radius of linear operators in Hilbert spaces, Bull. Austral. Math. Soc., 73 (2006), 255–262. https://doi.org/10.1017/S0004972700038831 doi: 10.1017/S0004972700038831 |
[6] | S. S. Dragomir, Some inequalities for the norm and the numerical radius of linear operators in Hilbert Spaces, Tamkang J. Math., 39 (2008). https://doi.org/10.5556/j.tkjm.39.2008.40 doi: 10.5556/j.tkjm.39.2008.40 |
[7] | S. S. Dragomir, Power inequalities for the numarical radius of a product of two operators in Hilbert spaces, Res. Rep. Collect., 11 (2008), 269–278. |
[8] | S. S. Dragomir, Some inequalities generalizing Kato's and Furuta's results, Filomat, 28 (2014), 179–195. https://doi.10.2298/FIL1401179D doi: 10.2298/FIL1401179D |
[9] | S. Furuichi, Further improvements of Young inequality, Rev. R. Acad. Cienc. Exactas Fis. Nat. Ser. A Mat., 113 (2019), 255–266. https://doi.org/10.1007/s13398-017-0469-5 doi: 10.1007/s13398-017-0469-5 |
[10] | K. Gustafson, D. Rao, Numerical Range, New York: Springer-Verlage, 1997. https://doi.org/10.1007/978-1-4613-8498-4_1 |
[11] | F. Kubo, T. Ando, Means of positive linear operators, Math. Ann., 246 (1980), 205–224. https://doi.org/10.1007/BF01371042 doi: 10.1007/BF01371042 |
[12] | F. Kittaneh, Notes on some inequalities for Hilbert Space operators, Publ Res. Inst. Math. Sci., 24 (1988), 283–293. https://doi.org/10.2977/PRIMS/1195175202 doi: 10.2977/PRIMS/1195175202 |
[13] | F. Kittaneh, A numerical radius inequality and an estimate for the numerical radius of the Frobenius companion matrix, Studia Math., 158 (2003), 11–17. https://doi.org/10.4064/sm158-1-2 doi: 10.4064/sm158-1-2 |
[14] | F. Kittaneh, Numerical radius inequalities for Hilbert space operators, Studia Math., 168 (2005), 73–80. http://eudml.org/doc/284514 |
[15] | F. Kittaneh, M. El-Haddad, Numerical radius inequalities for Hilbert space operators Ⅱ, Studia Math., 182 (2007), 133–140. https://doi.org/10.4064/sm182-2-3 doi: 10.4064/sm182-2-3 |
[16] | F. Kittaneh, Y. Manasrah, Improved Young and Heinz inequalities for matrices, J. Math. Anal. Appl., 361 (2010), 262–269. https://doi.org/10.1016/j.jmaa.2009.08.059 doi: 10.1016/j.jmaa.2009.08.059 |
[17] | Y. A. Manasrah, F. Kittaneh, A generalization of two refined Young inequalities, Positivity, 19 (2015), 757–768. https://doi.org/10.1007/s11117-015-0326-8 doi: 10.1007/s11117-015-0326-8 |
[18] | B. Mond, J. Pečarić, On Jensen's inequality for operator convex functions, Houston J. Math., 21 (1995), 739–753. |
[19] | M. H. M. Rashid, Power inequalities for the numerical radius of operators in Hilbert spaces, Khayyam J. Math., 5 (2019), 15–29. https://doi.org/10.22034/kjm.2019.84204 doi: 10.22034/kjm.2019.84204 |
[20] | M. H. M. Rashid, N. H. Altaweel, Numerical range of generalized aluthge transformation, Informatica J., 32 (2021), 2–11. |
[21] | M. H. M. Rashid, N. H. Altaweel, Some generalized numerical radius inequalities for Hilbert space operators, J. Math. Ineq., 16 (2022), 541–560. http://dx.doi.org/10.7153/jmi-2022-16-39 doi: 10.7153/jmi-2022-16-39 |
[22] | M. H. M. Rashid, Refinements of some numerical radius inequalities for Hilbert space operators, Tamkang J.Math., 54 (2023), 155–173. https://doi.org/10.5556/j.tkjm.54.2023.4061 doi: 10.5556/j.tkjm.54.2023.4061 |
[23] | K. Shebrawi, H. Albadwi, Numerical radius and operator norm inequalities, J. Inequal. Appl., 11 (2009), 492154. https://doi.org/10.1155/2009/492154 doi: 10.1155/2009/492154 |
[24] | S. Tafazoli, H. R. Moradi, S. Furuichi, P. Harikrishnan, Further inequalities for the numerical radius of Hilbert space operators, J. Math. Ineq., 13 (2019), 955–967. |