关于在半平面内绝对收敛的某类实系数狄利克列数列

Q3 Mathematics Matematychni Studii Pub Date : 2024-03-19 DOI:10.30970/ms.61.1.35-50
M. Sheremeta
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Sheremeta","doi":"10.30970/ms.61.1.35-50","DOIUrl":null,"url":null,"abstract":" For $h>0$, $\\alpha\\in [0,h)$ and $\\mu\\in {\\mathbb R}$  denote by   $SD_h(\\mu, \\alpha)$ a class \nof absolutely convergent in the half-plane $\\Pi_0=\\{s:\\, \\text{Re}\\,s<0\\}$ Dirichlet series \n$F(s)=e^{sh}+\\sum_{k=1}^{\\infty}f_k\\exp\\{s\\lambda_k\\}$ such that \n  \n\\smallskip\\centerline{$\\text{Re}\\left\\{\\frac{(\\mu-1)F'(s)-\\mu F''(s)/h}{(\\mu-1)F(s)-\\mu F'(s)/h}\\right\\}>\\alpha$ for all $s\\in \\Pi_0$,} \n  \n\\smallskip\\noi and \nlet  $\\Sigma D_h(\\mu, \\alpha)$ be a class of absolutely convergent in half-plane $\\Pi_0$ Dirichlet series \n$F(s)=e^{-sh}+\\sum_{k=1}^{\\infty}f_k\\exp\\{s\\lambda_k\\}$ such that \n  \n\\smallskip\\centerline{$\\text{Re}\\left\\{\\frac{(\\mu-1)F'(s)+\\mu F''(s)/h}{(\\mu-1)F(s)+\\mu F'(s)/h}\\right\\}<-\\alpha$ for all $s\\in \\Pi_0$.} \n  \n\\smallskip\\noi \nThen $SD_h(0, \\alpha)$ consists of pseudostarlike functions of order $\\alpha$ and $SD_h(1, \\alpha)$ consists of pseudoconvex functions of order $\\alpha$. \n  \nFor functions from the classes  $SD_h(\\mu, \\alpha)$ and  $\\Sigma D_h(\\mu, \\alpha)$, estimates for the coefficients and growth estimates are obtained. {In particular, it is proved the following statements:  1) In order that function $F(s)=e^{sh}+\\sum_{k=1}^{\\infty}f_k\\exp\\{s\\lambda_k\\}$ belongs to \n$SD_h(\\mu, \\alpha)$, it is \nsufficient, and in the case when $f_k(\\mu\\lambda_k/h-\\mu+1)\\le 0$ for all $k\\ge 1$, it is necessary that} \n  \n\\smallskip\\centerline{$ \n\\sum\\limits_{k=1}^{\\infty}\\big|f_k\\big(\\frac{\\mu\\lambda_k}{h}-\\mu+1\\big)\\big|(\\lambda_k-\\alpha)\\le h-\\alpha,$} \n  \n\\noi {where $h>0, \\alpha\\in [0, h)$ (Theorem 1).} \n  \n\\noi 2) {In order that function $F(s)=e^{-sh}+\\sum_{k=1}^{\\infty}f_k\\exp\\{s\\lambda_k\\}$ belongs to $\\Sigma D_h(\\mu, \\alpha)$, it is \nsufficient, and in the case when $f_k(\\mu\\lambda_k/h+\\mu-1)\\le 0$ for all $k\\ge 1$, it is necessary that \n  \n\\smallskip\\centerline{$\\sum\\limits_{k=1}^{\\infty}\\big|f_k\\big(\\frac{\\mu\\lambda_k}{h}+\\mu-1\\big)\\big|(\\lambda_k+\\alpha)\\le h-\\alpha,$} \n  \n\\noi where $h>0,  \\alpha\\in [0, h)$ (Theorem~2).}  Neighborhoods of such functions are investigated. Ordinary Hadamard compositions and Hadamard compositions of the genus $m$ were also studied.","PeriodicalId":37555,"journal":{"name":"Matematychni Studii","volume":" 2","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"On certain classes of Dirichlet series with real coefficients absolute convergent in a half-plane\",\"authors\":\"M. Sheremeta\",\"doi\":\"10.30970/ms.61.1.35-50\",\"DOIUrl\":null,\"url\":null,\"abstract\":\" For $h>0$, $\\\\alpha\\\\in [0,h)$ and $\\\\mu\\\\in {\\\\mathbb R}$  denote by   $SD_h(\\\\mu, \\\\alpha)$ a class \\nof absolutely convergent in the half-plane $\\\\Pi_0=\\\\{s:\\\\, \\\\text{Re}\\\\,s<0\\\\}$ Dirichlet series \\n$F(s)=e^{sh}+\\\\sum_{k=1}^{\\\\infty}f_k\\\\exp\\\\{s\\\\lambda_k\\\\}$ such that \\n  \\n\\\\smallskip\\\\centerline{$\\\\text{Re}\\\\left\\\\{\\\\frac{(\\\\mu-1)F'(s)-\\\\mu F''(s)/h}{(\\\\mu-1)F(s)-\\\\mu F'(s)/h}\\\\right\\\\}>\\\\alpha$ for all $s\\\\in \\\\Pi_0$,} \\n  \\n\\\\smallskip\\\\noi and \\nlet  $\\\\Sigma D_h(\\\\mu, \\\\alpha)$ be a class of absolutely convergent in half-plane $\\\\Pi_0$ Dirichlet series \\n$F(s)=e^{-sh}+\\\\sum_{k=1}^{\\\\infty}f_k\\\\exp\\\\{s\\\\lambda_k\\\\}$ such that \\n  \\n\\\\smallskip\\\\centerline{$\\\\text{Re}\\\\left\\\\{\\\\frac{(\\\\mu-1)F'(s)+\\\\mu F''(s)/h}{(\\\\mu-1)F(s)+\\\\mu F'(s)/h}\\\\right\\\\}<-\\\\alpha$ for all $s\\\\in \\\\Pi_0$.} \\n  \\n\\\\smallskip\\\\noi \\nThen $SD_h(0, \\\\alpha)$ consists of pseudostarlike functions of order $\\\\alpha$ and $SD_h(1, \\\\alpha)$ consists of pseudoconvex functions of order $\\\\alpha$. \\n  \\nFor functions from the classes  $SD_h(\\\\mu, \\\\alpha)$ and  $\\\\Sigma D_h(\\\\mu, \\\\alpha)$, estimates for the coefficients and growth estimates are obtained. {In particular, it is proved the following statements:  1) In order that function $F(s)=e^{sh}+\\\\sum_{k=1}^{\\\\infty}f_k\\\\exp\\\\{s\\\\lambda_k\\\\}$ belongs to \\n$SD_h(\\\\mu, \\\\alpha)$, it is \\nsufficient, and in the case when $f_k(\\\\mu\\\\lambda_k/h-\\\\mu+1)\\\\le 0$ for all $k\\\\ge 1$, it is necessary that} \\n  \\n\\\\smallskip\\\\centerline{$ \\n\\\\sum\\\\limits_{k=1}^{\\\\infty}\\\\big|f_k\\\\big(\\\\frac{\\\\mu\\\\lambda_k}{h}-\\\\mu+1\\\\big)\\\\big|(\\\\lambda_k-\\\\alpha)\\\\le h-\\\\alpha,$} \\n  \\n\\\\noi {where $h>0, \\\\alpha\\\\in [0, h)$ (Theorem 1).} \\n  \\n\\\\noi 2) {In order that function $F(s)=e^{-sh}+\\\\sum_{k=1}^{\\\\infty}f_k\\\\exp\\\\{s\\\\lambda_k\\\\}$ belongs to $\\\\Sigma D_h(\\\\mu, \\\\alpha)$, it is \\nsufficient, and in the case when $f_k(\\\\mu\\\\lambda_k/h+\\\\mu-1)\\\\le 0$ for all $k\\\\ge 1$, it is necessary that \\n  \\n\\\\smallskip\\\\centerline{$\\\\sum\\\\limits_{k=1}^{\\\\infty}\\\\big|f_k\\\\big(\\\\frac{\\\\mu\\\\lambda_k}{h}+\\\\mu-1\\\\big)\\\\big|(\\\\lambda_k+\\\\alpha)\\\\le h-\\\\alpha,$} \\n  \\n\\\\noi where $h>0,  \\\\alpha\\\\in [0, h)$ (Theorem~2).}  Neighborhoods of such functions are investigated. 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引用次数: 0

摘要

对于 $h>0$, $\alpha\in [0,h)$ 和 $\mu\in {\mathbb R}$,用 $SD_h(\mu, \alpha)$ 表示在半平面 $\Pi_0=\{s:\对于所有 $s\in \Pi_0$,} \smallskip\noi 并让 $\Sigma D_h(\mu、讓 $Sigma D_h(\mu, \alpha)$ 是一類絕對收斂的半平面 $\Pi_0$ Dirichlet 數列 $F(s)=e^{-sh}+\sum_{k=1}^{\infty}f_k\exp\{s\lambda_k\}$ such that \smallskip\centerline{$\text{Re}\left\{\frac{(\mu-1)F'(s)+\mu F''(s)/h}{(\mu-1)F(s)+\mu F'(s)/h}\right\}0,\在 [0, h]$(定理 1)。} \2) {为了使函数$F(s)=e^{-sh}+\sum_{k=1}^{\infty}f_kexp\{s\lambda_k\}$ 属于$\Sigma D_h(\mu,\alpha)$,这就足够了,并且在所有$kge 1$的情况下,当$f_k(\mu\lambda_k/h+\mu-1)\le 0$时、it is necessary that \smallskip\centerline{$\sum\limits_{k=1}^{\infty}\big|f_k\big(\frac\{mu\lambda_k}{h}+\mu-1\big)\big|(\lambda_k+\alpha)\le h-\alpha,$}. \其中 $h>0, \alpha\in [0, h)$ (定理~2)}。 对这些函数的邻域进行了研究。还研究了普通哈达玛组合和属$m$的哈达玛组合。
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On certain classes of Dirichlet series with real coefficients absolute convergent in a half-plane
 For $h>0$, $\alpha\in [0,h)$ and $\mu\in {\mathbb R}$  denote by   $SD_h(\mu, \alpha)$ a class of absolutely convergent in the half-plane $\Pi_0=\{s:\, \text{Re}\,s<0\}$ Dirichlet series $F(s)=e^{sh}+\sum_{k=1}^{\infty}f_k\exp\{s\lambda_k\}$ such that   \smallskip\centerline{$\text{Re}\left\{\frac{(\mu-1)F'(s)-\mu F''(s)/h}{(\mu-1)F(s)-\mu F'(s)/h}\right\}>\alpha$ for all $s\in \Pi_0$,}   \smallskip\noi and let  $\Sigma D_h(\mu, \alpha)$ be a class of absolutely convergent in half-plane $\Pi_0$ Dirichlet series $F(s)=e^{-sh}+\sum_{k=1}^{\infty}f_k\exp\{s\lambda_k\}$ such that   \smallskip\centerline{$\text{Re}\left\{\frac{(\mu-1)F'(s)+\mu F''(s)/h}{(\mu-1)F(s)+\mu F'(s)/h}\right\}<-\alpha$ for all $s\in \Pi_0$.}   \smallskip\noi Then $SD_h(0, \alpha)$ consists of pseudostarlike functions of order $\alpha$ and $SD_h(1, \alpha)$ consists of pseudoconvex functions of order $\alpha$.   For functions from the classes  $SD_h(\mu, \alpha)$ and  $\Sigma D_h(\mu, \alpha)$, estimates for the coefficients and growth estimates are obtained. {In particular, it is proved the following statements:  1) In order that function $F(s)=e^{sh}+\sum_{k=1}^{\infty}f_k\exp\{s\lambda_k\}$ belongs to $SD_h(\mu, \alpha)$, it is sufficient, and in the case when $f_k(\mu\lambda_k/h-\mu+1)\le 0$ for all $k\ge 1$, it is necessary that}   \smallskip\centerline{$ \sum\limits_{k=1}^{\infty}\big|f_k\big(\frac{\mu\lambda_k}{h}-\mu+1\big)\big|(\lambda_k-\alpha)\le h-\alpha,$}   \noi {where $h>0, \alpha\in [0, h)$ (Theorem 1).}   \noi 2) {In order that function $F(s)=e^{-sh}+\sum_{k=1}^{\infty}f_k\exp\{s\lambda_k\}$ belongs to $\Sigma D_h(\mu, \alpha)$, it is sufficient, and in the case when $f_k(\mu\lambda_k/h+\mu-1)\le 0$ for all $k\ge 1$, it is necessary that   \smallskip\centerline{$\sum\limits_{k=1}^{\infty}\big|f_k\big(\frac{\mu\lambda_k}{h}+\mu-1\big)\big|(\lambda_k+\alpha)\le h-\alpha,$}   \noi where $h>0,  \alpha\in [0, h)$ (Theorem~2).}  Neighborhoods of such functions are investigated. Ordinary Hadamard compositions and Hadamard compositions of the genus $m$ were also studied.
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Matematychni Studii
Matematychni Studii Mathematics-Mathematics (all)
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期刊介绍: Journal is devoted to research in all fields of mathematics.
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On the h-measure of an exceptional set in Fenton-type theorem for Taylor-Dirichlet series Almost periodic distributions and crystalline measures Reflectionless Schrodinger operators and Marchenko parametrization Existence of basic solutions of first order linear homogeneous set-valued differential equations Real univariate polynomials with given signs of coefficients and simple real roots
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