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Boundary curvature of the numerical range of self-inverse operators | ||
| International Journal of Nonlinear Analysis and Applications | ||
| مقاله 4، دوره 16، شماره 5، مرداد 2025، صفحه 35-42 اصل مقاله (324.02 K) | ||
| نوع مقاله: Research Paper | ||
| شناسه دیجیتال (DOI): 10.22075/ijnaa.2024.33147.4935 | ||
| نویسندگان | ||
| Seyyed Nematollah Khademi1؛ Mohammad Taghi Heydari* 2؛ Vahid Keshavarz1 | ||
| 1Department of Mathematics, College of Sciences, Yasouj University, Yasouj, 75918 Iran | ||
| 2Department of Mathematics, College of Sciences, Yasouj Univer- sity, Yasouj, 75918, Iran | ||
| تاریخ دریافت: 11 بهمن 1402، تاریخ بازنگری: 21 فروردین 1403، تاریخ پذیرش: 10 اردیبهشت 1403 | ||
| چکیده | ||
| In this article, firstly we investigate some properties of the boundary curvature of the numerical range. In the next, we define $M(T)$ as the smallest constant such that $dist(\lambda,\sigma(T))\leq M(T) R_\lambda (T),$ for all $\lambda \in \partial W(T)$, where $R_\lambda (T)$, the radius curvature at the point $\lambda$, is defined. Also, we investigate for non-convexoid $T$, $M(T)=\sup\frac{dist(\lambda,\sigma(T))}{R_{\lambda}(T)}$, where the supremum on the right-hand side is taken along all points $\lambda\in \partial W(T)$ with finite non-zero curvature. Finally, the value of $M(T)$ will be calculated for the self-inverse operators. | ||
| کلیدواژه‌ها | ||
| Boundary Curvature؛ Numerical range؛ Self-Inverse Operators | ||
| مراجع | ||
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