{"title":"具有零计数函数缓慢增长的blaschke积的对数导数","authors":"Y. Gal, M. Zabolotskyi, M. Mostova","doi":"10.31861/bmj2021.01.13","DOIUrl":null,"url":null,"abstract":"The Blaschke products form an important subclass of analytic functions on the unit disc with bounded Nevanlinna characteristic and also are meromorphic functions on $\\mathbb{C}$ except for the accumulation points of zeros $B(z)$.\nAsymptotics and estimates of the logarithmic derivative of meromorphic functions play an important role in various fields of mathematics. In particular, such problems in Nevanlinna's theory of value distribution were studied by Goldberg A.A., Korenkov N.E., Hayman W.K., Miles J. and in the analytic theory of differential equations -- by Chyzhykov I.E., Strelitz Sh.I.\n\nLet $z_0=1$ be the only boundary point of zeros $(a_n)$ %=1-r_ne^{i\\psi_n},$ $-\\pi/2+\\eta<\\psi_n<\\pi/2-\\eta,$ $r_n\\to0+$ as $n\\to+\\infty,$\nof the Blaschke product $B(z);$ $\\Gamma_m=\\bigcup\\limits_{j=1}^{m}\\{z:|z|<1,\\mathop{\\text{arg}}(1-z)=-\\theta_j\\}=\\bigcup\\limits_{j=1}^{m}l_{\\theta_j},$ $-\\pi/2+\\eta<\\theta_1<\\theta_2<\\ldots<\\theta_m<\\pi/2-\\eta,$ be a finite system of rays, $0<\\eta<1$; $\\upsilon(t)$ be continuous on $[0,1)$, $\\upsilon(0)=0$, slowly increasing at the point 1 function, that is $\\upsilon(t)\\sim\\upsilon\\left({(1+t)}/2\\right),$ $t\\to1-;$ $n(t,\\theta_j;B)$ be a number of zeros $a_n=1-r_ne^{i\\theta_j}$ of the product $B(z)$ on the ray $l_{\\theta_j}$ such that $1-r_n\\leq t,$ $0<t<1.$ We found asymptotics of the logarithmic derivative of $B(z)$ as $z=1-re^{-i\\varphi}\\to1,$ $-\\pi/2<\\varphi<\\pi/2,$ $\\varphi\\neq\\theta_j,$ under the condition that zeros of $B(z)$ lay on $\\Gamma_m$ and $n(t,\\theta_j;B)\\sim \\Delta_j\\upsilon(t),$ $t\\to1-,$ for all $j=\\overline{1,m},$ $0\\leq\\Delta_j<+\\infty.$ We also considered the inverse problem for such $B(z).$","PeriodicalId":196726,"journal":{"name":"Bukovinian Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"LOGARITHMIC DERIVATIVE OF THE BLASCHKE PRODUCT WITH SLOWLY INCREASING COUNTING FUNCTION OF ZEROS\",\"authors\":\"Y. Gal, M. Zabolotskyi, M. Mostova\",\"doi\":\"10.31861/bmj2021.01.13\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"The Blaschke products form an important subclass of analytic functions on the unit disc with bounded Nevanlinna characteristic and also are meromorphic functions on $\\\\mathbb{C}$ except for the accumulation points of zeros $B(z)$.\\nAsymptotics and estimates of the logarithmic derivative of meromorphic functions play an important role in various fields of mathematics. In particular, such problems in Nevanlinna's theory of value distribution were studied by Goldberg A.A., Korenkov N.E., Hayman W.K., Miles J. and in the analytic theory of differential equations -- by Chyzhykov I.E., Strelitz Sh.I.\\n\\nLet $z_0=1$ be the only boundary point of zeros $(a_n)$ %=1-r_ne^{i\\\\psi_n},$ $-\\\\pi/2+\\\\eta<\\\\psi_n<\\\\pi/2-\\\\eta,$ $r_n\\\\to0+$ as $n\\\\to+\\\\infty,$\\nof the Blaschke product $B(z);$ $\\\\Gamma_m=\\\\bigcup\\\\limits_{j=1}^{m}\\\\{z:|z|<1,\\\\mathop{\\\\text{arg}}(1-z)=-\\\\theta_j\\\\}=\\\\bigcup\\\\limits_{j=1}^{m}l_{\\\\theta_j},$ $-\\\\pi/2+\\\\eta<\\\\theta_1<\\\\theta_2<\\\\ldots<\\\\theta_m<\\\\pi/2-\\\\eta,$ be a finite system of rays, $0<\\\\eta<1$; $\\\\upsilon(t)$ be continuous on $[0,1)$, $\\\\upsilon(0)=0$, slowly increasing at the point 1 function, that is $\\\\upsilon(t)\\\\sim\\\\upsilon\\\\left({(1+t)}/2\\\\right),$ $t\\\\to1-;$ $n(t,\\\\theta_j;B)$ be a number of zeros $a_n=1-r_ne^{i\\\\theta_j}$ of the product $B(z)$ on the ray $l_{\\\\theta_j}$ such that $1-r_n\\\\leq t,$ $0<t<1.$ We found asymptotics of the logarithmic derivative of $B(z)$ as $z=1-re^{-i\\\\varphi}\\\\to1,$ $-\\\\pi/2<\\\\varphi<\\\\pi/2,$ $\\\\varphi\\\\neq\\\\theta_j,$ under the condition that zeros of $B(z)$ lay on $\\\\Gamma_m$ and $n(t,\\\\theta_j;B)\\\\sim \\\\Delta_j\\\\upsilon(t),$ $t\\\\to1-,$ for all $j=\\\\overline{1,m},$ $0\\\\leq\\\\Delta_j<+\\\\infty.$ We also considered the inverse problem for such $B(z).$\",\"PeriodicalId\":196726,\"journal\":{\"name\":\"Bukovinian Mathematical Journal\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"1900-01-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Bukovinian Mathematical Journal\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.31861/bmj2021.01.13\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Bukovinian Mathematical Journal","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.31861/bmj2021.01.13","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
摘要
Blaschke积是具有有界Nevanlinna特征的单位圆盘上解析函数的一个重要子类,除了0的累加点$B(z)$外,也是$\mathbb{C}$上的亚纯函数。亚纯函数的对数导数的渐近性和估计在数学的各个领域中起着重要的作用。特别是,Goldberg a.a., Korenkov n.e., Hayman w.k., Miles j在Nevanlinna的值分布理论和Chyzhykov i.e., Strelitz sh . i在微分方程解析理论中研究了这类问题。设$z_0=1$为零的唯一边界点 $(a_n)$ %=1-r_ne^{i\psi_n},$ $-\pi/2+\eta<\psi_n<\pi/2-\eta,$ $r_n\to0+$ as $n\to+\infty,$of the Blaschke product $B(z);$ $\Gamma_m=\bigcup\limits_{j=1}^{m}\{z:|z|<1,\mathop{\text{arg}}(1-z)=-\theta_j\}=\bigcup\limits_{j=1}^{m}l_{\theta_j},$ $-\pi/2+\eta<\theta_1<\theta_2<\ldots<\theta_m<\pi/2-\eta,$ be a finite system of rays, $0<\eta<1$; $\upsilon(t)$ be continuous on $[0,1)$, $\upsilon(0)=0$, slowly increasing at the point 1 function, that is $\upsilon(t)\sim\upsilon\left({(1+t)}/2\right),$ $t\to1-;$ $n(t,\theta_j;B)$ be a number of zeros $a_n=1-r_ne^{i\theta_j}$ of the product $B(z)$ on the ray $l_{\theta_j}$ such that $1-r_n\leq t,$ $0本文章由计算机程序翻译,如有差异,请以英文原文为准。
LOGARITHMIC DERIVATIVE OF THE BLASCHKE PRODUCT WITH SLOWLY INCREASING COUNTING FUNCTION OF ZEROS
The Blaschke products form an important subclass of analytic functions on the unit disc with bounded Nevanlinna characteristic and also are meromorphic functions on $\mathbb{C}$ except for the accumulation points of zeros $B(z)$.
Asymptotics and estimates of the logarithmic derivative of meromorphic functions play an important role in various fields of mathematics. In particular, such problems in Nevanlinna's theory of value distribution were studied by Goldberg A.A., Korenkov N.E., Hayman W.K., Miles J. and in the analytic theory of differential equations -- by Chyzhykov I.E., Strelitz Sh.I.
Let $z_0=1$ be the only boundary point of zeros $(a_n)$ %=1-r_ne^{i\psi_n},$ $-\pi/2+\eta<\psi_n<\pi/2-\eta,$ $r_n\to0+$ as $n\to+\infty,$
of the Blaschke product $B(z);$ $\Gamma_m=\bigcup\limits_{j=1}^{m}\{z:|z|<1,\mathop{\text{arg}}(1-z)=-\theta_j\}=\bigcup\limits_{j=1}^{m}l_{\theta_j},$ $-\pi/2+\eta<\theta_1<\theta_2<\ldots<\theta_m<\pi/2-\eta,$ be a finite system of rays, $0<\eta<1$; $\upsilon(t)$ be continuous on $[0,1)$, $\upsilon(0)=0$, slowly increasing at the point 1 function, that is $\upsilon(t)\sim\upsilon\left({(1+t)}/2\right),$ $t\to1-;$ $n(t,\theta_j;B)$ be a number of zeros $a_n=1-r_ne^{i\theta_j}$ of the product $B(z)$ on the ray $l_{\theta_j}$ such that $1-r_n\leq t,$ $0