Geometric properties of a generalized linear operator acting on univalent functions
UDC 517.53 Let \(f\) be an analytic and univalent function in an open unit disk \(\mathbb{D}\) that belongs to certain subclasses, such as starlike, convex, or close-to-convex functions. For the parameters \(\alpha, \beta \in [0,1]\) such that \(\alpha + \beta \le 1,\) we define a function\[g_{\alph...
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| Date: | 2026 |
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| Main Authors: | , |
| Format: | Article |
| Language: | English |
| Published: |
Institute of Mathematics, NAS of Ukraine
2026
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| Online Access: | https://umj.imath.kiev.ua/index.php/umj/article/view/9414 |
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| Journal Title: | Ukrains’kyi Matematychnyi Zhurnal |
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Ukrains’kyi Matematychnyi Zhurnal| Summary: | UDC 517.53
Let \(f\) be an analytic and univalent function in an open unit disk \(\mathbb{D}\) that belongs to certain subclasses, such as starlike, convex, or close-to-convex functions. For the parameters \(\alpha, \beta \in [0,1]\) such that \(\alpha + \beta \le 1,\) we define a function\[g_{\alpha,\beta}(z) = (1-\alpha-\beta)f(z) + (\alpha+\beta) z f'(z),\] which represents a convex-type combination of the identity operator and the classical differential operator. We investigate the conditions under which the function \(g_{\alpha,\beta}(z)\) generated by a generalized linear operator preserves the geometric properties of the original function \(f\) with particular emphasis on radius problems related to univalence and distortion behavior. Explicit radius bounds are deduced by using classical analytic techniques. In addition, AI-assisted numerical experiments are used to verify the sharpness of the theoretical results and to illustrate the dependence of the radius functions on the parameters \(\alpha\) and \(\beta.\) Representative numerical values and graphical visualizations are provided. |
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| DOI: | 10.3842/umzh.v78i3-4.9414 |