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Improvement of the Gr\"{u}ss type inequalities for positive linear maps on $C^{*}$-algebras | ||
Caspian Journal of Mathematical Sciences | ||
دوره 12، شماره 1 - شماره پیاپی 23، 2023، صفحه 81-93 اصل مقاله (151.32 K) | ||
نوع مقاله: Research Articles | ||
شناسه دیجیتال (DOI): 10.22080/cjms.2022.23689.1629 | ||
نویسندگان | ||
Fatemeh Golfarshchi* 1؛ Ali Asghar Khalilzadeh2؛ Feridoon Moradlou3 | ||
1Tabriz Islamic Art University | ||
2Department of Mathematics, Sahand University of Technology, Tabriz, Iran | ||
3Department of Mathematics Sahand University of Technology | ||
تاریخ دریافت: 21 خرداد 1401، تاریخ بازنگری: 29 مرداد 1401، تاریخ پذیرش: 19 شهریور 1401 | ||
چکیده | ||
Assume that $A$ and $B$ are unital $C^{*}$-algebras and $\varphi:A\rightarrow B$ is a unital positive linear map. We show that if $B$ is commutative, then for all $x,y \in A$ and $\alpha, \beta \in \mathbb{C}$ \begin{align*} |\varphi(xy)-\varphi(x)\varphi(y)| \leq & \left[ \varphi(|x^{*}-\alpha 1_{A}|^{2})\right] ^{\frac{1}{2}}\left[\varphi(|y-\beta1_{A}|^{2})\right] ^{\frac{1}{2}} \\ & - |\varphi(x^{*}-\alpha 1_{A})| |\varphi(y-\beta1_{A})|. \end{align*} Furthermore, we prove that if $z\in A$ with $|z| =1$ and $\lambda, \mu \in \mathbb{C}$ are such that $Re(\varphi((x^{*}-\bar{\beta}z^{*})(\alpha z-x)))\geq 0$ and $Re(\varphi((y^{*}-\bar{\mu}z^{*})(\lambda z-y)))\geq 0$, then \begin{center} $|\varphi(x^{*}y)-\varphi(x^{*}z)\varphi(z^{*}y)| \leq \frac{1}{4}| \beta-\alpha | | \mu-\alpha | -$ \\ $ \left[ Re(\varphi((x^{*}-\bar{\beta}z^{*})(\alpha z-x)))\right] ^{\frac{1}{2}}\left[ Re(\varphi((y^{*}-\bar{\mu}z^{*})(\lambda z-y)))\right] ^{\frac{1}{2}}.$ \end{center} The presented bounds for the Gr\"{u}ss type inequalities on $C^{*}$-algebras improve the other ones in the literature under mild conditions. As an application, using our results, we give some inequalities in $L^{\infty}(\left[a,b\right])$, which refine the other ones in the literature. | ||
کلیدواژهها | ||
$C^{*}$-algebras؛ Gr\"{u}ss type inequalities؛ Positive linear map | ||
آمار تعداد مشاهده مقاله: 120 تعداد دریافت فایل اصل مقاله: 74 |