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Douady–Earle Extensions of Circle Homeomorphisms with One-Point Differentiability at a Hölder Convergence Rate 圆同构的杜阿迪-厄尔扩展与赫尔德收敛率下的单点可微分性
IF 2.1 4区 数学
Computational Methods and Function Theory Pub Date : 2024-04-17 DOI: 10.1007/s40315-024-00540-9
Jinhua Fan, Jun Hu, Zhenyong Hu
{"title":"Douady–Earle Extensions of Circle Homeomorphisms with One-Point Differentiability at a Hölder Convergence Rate","authors":"Jinhua Fan, Jun Hu, Zhenyong Hu","doi":"10.1007/s40315-024-00540-9","DOIUrl":"https://doi.org/10.1007/s40315-024-00540-9","url":null,"abstract":"<p>Let <i>h</i> be a sense-preserving homeomorphism of the unit circle <span>({mathbb {S}})</span> and <span>(Phi (h))</span> the Douady–Earle extension of <i>h</i> to the closure of the open disk <span>({mathbb {D}})</span>. In this paper, assuming that <i>h</i> is differentiable at a point <span>(xi in {mathbb {S}})</span> with <span>(alpha )</span>-Hölder convergence rate for some <span>(0&lt;alpha &lt;1)</span>, we prove a similar regularity for <span>(Phi (h))</span> near <span>(xi )</span> on <span>({mathbb {D}})</span> in any non-tangential direction towards <span>(xi )</span>.</p>","PeriodicalId":49088,"journal":{"name":"Computational Methods and Function Theory","volume":"5 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140609372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Loewner PDE in Infinite Dimensions 无穷维度中的 Loewner PDE
IF 2.1 4区 数学
Computational Methods and Function Theory Pub Date : 2024-04-12 DOI: 10.1007/s40315-024-00536-5
Ian Graham, Hidetaka Hamada, Gabriela Kohr, Mirela Kohr
{"title":"Loewner PDE in Infinite Dimensions","authors":"Ian Graham, Hidetaka Hamada, Gabriela Kohr, Mirela Kohr","doi":"10.1007/s40315-024-00536-5","DOIUrl":"https://doi.org/10.1007/s40315-024-00536-5","url":null,"abstract":"<p>In this paper, we prove the existence and uniqueness of the solution <i>f</i>(<i>z</i>, <i>t</i>) of the Loewner PDE with normalization <span>(Df(0,t)=e^{tA})</span>, where <span>(Ain L(X,X))</span> is such that <span>(k_+(A)&lt;2m(A))</span>, on the unit ball of a separable reflexive complex Banach space <i>X</i>. In particular, we obtain the biholomorphicity of the univalent Schwarz mappings <i>v</i>(<i>z</i>, <i>s</i>, <i>t</i>) with normalization <span>(Dv(0,s,t)=e^{-(t-s)A})</span> for <span>(tge sge 0)</span>, where <span>(m(A)&gt;0)</span>, which satisfy the semigroup property on the unit ball of a complex Banach space <i>X</i>. We further obtain the biholomorphicity of <i>A</i>-normalized univalent subordination chains under some normality condition on the unit ball of a reflexive complex Banach space <i>X</i>. We prove the existence of the biholomorphic solutions <i>f</i>(<i>z</i>, <i>t</i>) of the Loewner PDE with normalization <span>(Df(0,t)=e^{tA})</span> on the unit ball of a separable reflexive complex Banach space <i>X</i>. The results obtained in this paper give some positive answers to the open problems and conjectures proposed by the authors in 2013.</p>","PeriodicalId":49088,"journal":{"name":"Computational Methods and Function Theory","volume":"37 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140570220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Distortion, Radius of Concavity and Several Other Radii Results for Certain Classes of Functions 若干类函数的畸变、凹半径和若干其他半径结果
IF 2.1 4区 数学
Computational Methods and Function Theory Pub Date : 2024-04-12 DOI: 10.1007/s40315-024-00525-8
Bappaditya Bhowmik, Souvik Biswas
{"title":"Distortion, Radius of Concavity and Several Other Radii Results for Certain Classes of Functions","authors":"Bappaditya Bhowmik, Souvik Biswas","doi":"10.1007/s40315-024-00525-8","DOIUrl":"https://doi.org/10.1007/s40315-024-00525-8","url":null,"abstract":"<p>Let <i>S</i>(<i>p</i>) be the class of all meromorphic univalent functions defined in the unit disc <span>({mathbb D})</span> of the complex plane with a simple pole at <span>(z=p)</span> and normalized by the conditions <span>(f(0)=0)</span> and <span>(f'(0)=1)</span>. In this article, we establish an estimate of the quantity <span>(|zf'/f|)</span> and obtain the region of variability of the function <span>(zf''/f')</span> for <span>(zin {mathbb D})</span>, <span>(fin S(p))</span>. After that, we define radius of concavity and compute the same for functions in <i>S</i>(<i>p</i>) and for some other well-known classes of functions. We also explore linear combinations of functions belonging to <i>S</i>(<i>p</i>) and some other classes of analytic univalent functions and investigate their radii of univalence, convexity and concavity.</p>","PeriodicalId":49088,"journal":{"name":"Computational Methods and Function Theory","volume":"37 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140570225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The Impact of the Limit q-Durrmeyer Operator on Continuous Functions 极限 q-Durrmeyer 算子对连续函数的影响
IF 2.1 4区 数学
Computational Methods and Function Theory Pub Date : 2024-04-09 DOI: 10.1007/s40315-024-00534-7
Övgü Gürel Yılmaz, Sofiya Ostrovska, Mehmet Turan
{"title":"The Impact of the Limit q-Durrmeyer Operator on Continuous Functions","authors":"Övgü Gürel Yılmaz, Sofiya Ostrovska, Mehmet Turan","doi":"10.1007/s40315-024-00534-7","DOIUrl":"https://doi.org/10.1007/s40315-024-00534-7","url":null,"abstract":"<p>The limit <i>q</i>-Durrmeyer operator, <span>(D_{infty ,q})</span>, was introduced and its approximation properties were investigated by Gupta (Appl. Math. Comput. 197(1):172–178, 2008) during a study of <i>q</i>-analogues for the Bernstein–Durrmeyer operator. In the present work, this operator is investigated from a different perspective. More precisely, the growth estimates are derived for the entire functions comprising the range of <span>(D_{infty ,q})</span>. The interrelation between the analytic properties of a function <i>f</i> and the rate of growth for <span>(D_{infty ,q}f)</span> are established, and the sharpness of the obtained results are demonstrated.</p>","PeriodicalId":49088,"journal":{"name":"Computational Methods and Function Theory","volume":"11 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140570062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
On Row Differential Inequalities Related to Normality and Quasi-normality 论与正态性和准正态性有关的行微分不等式
IF 2.1 4区 数学
Computational Methods and Function Theory Pub Date : 2024-04-08 DOI: 10.1007/s40315-024-00524-9
Tomer Manket, Shahar Nevo
{"title":"On Row Differential Inequalities Related to Normality and Quasi-normality","authors":"Tomer Manket, Shahar Nevo","doi":"10.1007/s40315-024-00524-9","DOIUrl":"https://doi.org/10.1007/s40315-024-00524-9","url":null,"abstract":"<p>We study connections between a new type of linear differential inequalities and normality or quasi-normality. We prove that if <span>(C&gt;0)</span>, <span>(kge 1)</span> and <span>(a_0(z),dots ,a_{k-1}(z))</span> are fixed holomorphic functions in a domain <i>D</i>, then the family of the holomorphic functions <i>f</i> in <i>D</i>, satisfying for every <span>(zin D)</span></p><span>$$begin{aligned} left| f^{(k)}(z) + a_{k-1}(z)f^{(k-1)}(z)+cdots +a_0(z)f(z)right| &lt; C end{aligned}$$</span><p>is quasi-normal in <i>D</i>. For the reversed sign of the inequality we show the following: Suppose that <span>(A,Bin {{mathbb {C}}})</span>, <span>(C&gt;0)</span> and <span>(mathcal {F})</span> is a family of meromorphic functions <i>f</i> satisfying for every <span>(zin D)</span></p><span>$$begin{aligned} left| f^{''}(z) + Af^{'}(z) + B f(z)right| &gt; C end{aligned}$$</span><p>and also at least one of the families <span>(left{ f'/f:fin mathcal {F}right} )</span> or <span>(left{ f''/f:fin mathcal {F}right} )</span> is normal. Then <span>(mathcal {F})</span> is quasi-normal in <i>D</i>.</p>","PeriodicalId":49088,"journal":{"name":"Computational Methods and Function Theory","volume":"40 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140570222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A Lower Bound on the Growth of Minimal Graphs 最小图增长的下限
IF 2.1 4区 数学
Computational Methods and Function Theory Pub Date : 2024-04-06 DOI: 10.1007/s40315-024-00532-9
Allen Weitsman
{"title":"A Lower Bound on the Growth of Minimal Graphs","authors":"Allen Weitsman","doi":"10.1007/s40315-024-00532-9","DOIUrl":"https://doi.org/10.1007/s40315-024-00532-9","url":null,"abstract":"<p>We show that for minimal graphs in <span>(R^3)</span> having 0 boundary values over simpy connected domains, the maximum over circles of radius r must be at least of the order <span>(r^{1/2})</span>.</p>","PeriodicalId":49088,"journal":{"name":"Computational Methods and Function Theory","volume":"81 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140570223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Julia Components of Transcendental Entire Functions with Multiply-Connected Wandering Domains 具有乘法连接徘徊域的超越全函数的 Julia 分量
IF 2.1 4区 数学
Computational Methods and Function Theory Pub Date : 2024-04-04 DOI: 10.1007/s40315-024-00521-y
{"title":"Julia Components of Transcendental Entire Functions with Multiply-Connected Wandering Domains","authors":"","doi":"10.1007/s40315-024-00521-y","DOIUrl":"https://doi.org/10.1007/s40315-024-00521-y","url":null,"abstract":"<h3>Abstract</h3> <p>We investigate some topological properties of Julia components, that is, connected components of the Julia set, of a transcendental entire function <em>f</em> with a multiply-connected wandering domain. If <em>C</em> is a Julia component with a bounded orbit, then we show that there exists a polynomial <em>P</em> such that <em>C</em> is homeomorphic to a Julia component of the Julia set of <em>P</em>. Furthermore if <em>C</em> is wandering, then <em>C</em> is a buried singleton component. Also we show that under some dynamical conditions, every such <em>C</em> is full and a buried component. The key for our proof is to show that some iterate of <em>f</em> can be regarded as a polynomial-like map on a suitable arbitrarily large bounded topological disk. As an application of this result, we show that a transcendental entire function having a wandering domain with a bounded orbit cannot have multiply-connected wandering domains.</p>","PeriodicalId":49088,"journal":{"name":"Computational Methods and Function Theory","volume":"82 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140570060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
On Bloch’s “Principle of Topological Continuity” 论布洛赫的 "拓扑连续性原理"
IF 2.1 4区 数学
Computational Methods and Function Theory Pub Date : 2024-04-04 DOI: 10.1007/s40315-024-00531-w
Walter Bergweiler, Alexandre Eremenko
{"title":"On Bloch’s “Principle of Topological Continuity”","authors":"Walter Bergweiler, Alexandre Eremenko","doi":"10.1007/s40315-024-00531-w","DOIUrl":"https://doi.org/10.1007/s40315-024-00531-w","url":null,"abstract":"<p>We discuss to what extent certain results about totally ramified values of entire and meromorphic functions remain valid if one relaxes the hypothesis that some value is totally ramified by assuming only that all islands over some Jordan domain are multiple. In particular, we prove a result suggested by Bloch which says that an entire function of order less than 1 has a simple island over at least one of two given Jordan domains with disjoint closures.</p>","PeriodicalId":49088,"journal":{"name":"Computational Methods and Function Theory","volume":"37 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140570483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Normality Criterion Concerning Total Derivatives of Holomorphic Functions in $$ {mathbb {C}}^n $$ 关于 $$ {mathbb {C}}^n $$ 中全态函数总衍生物的正态性标准
IF 2.1 4区 数学
Computational Methods and Function Theory Pub Date : 2024-04-03 DOI: 10.1007/s40315-024-00523-w
Molla Basir Ahamed, Sanju Mandal
{"title":"Normality Criterion Concerning Total Derivatives of Holomorphic Functions in $$ {mathbb {C}}^n $$","authors":"Molla Basir Ahamed, Sanju Mandal","doi":"10.1007/s40315-024-00523-w","DOIUrl":"https://doi.org/10.1007/s40315-024-00523-w","url":null,"abstract":"<p>This paper continues investigation of conditions involving values shared by holomorphic functions and their total derivatives which imply the normality for a family of holomorphic functions concerning the total derivatives in <span>( {mathbb {C}}^n )</span>. Consequently, we obtain normality criterion of a family <span>( {mathcal {F}} )</span> of holomorphic functions <i>f</i>, where each function shares complex values with their linear total differential polynomials <span>( L_D^k(f) )</span> in <span>( {mathbb {C}}^n )</span>.</p>","PeriodicalId":49088,"journal":{"name":"Computational Methods and Function Theory","volume":"106 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140603103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Critical Points for Least-Squares Estimation of Dipolar Sources in Inverse Problems for Poisson Equation 泊松方程反问题中双极性源最小二乘估计的临界点
IF 2.1 4区 数学
Computational Methods and Function Theory Pub Date : 2024-04-03 DOI: 10.1007/s40315-024-00535-6
Paul Asensio, Juliette Leblond
{"title":"Critical Points for Least-Squares Estimation of Dipolar Sources in Inverse Problems for Poisson Equation","authors":"Paul Asensio, Juliette Leblond","doi":"10.1007/s40315-024-00535-6","DOIUrl":"https://doi.org/10.1007/s40315-024-00535-6","url":null,"abstract":"<p>In this work, we study some aspects of the solvability of the minimization of a non-convex least-squares criterion involved in dipolar source recovery issues, using boundary values of a solution to a Poisson problem in a domain of dimension 3. This Poisson problem arises in particular from the quasi-static approximation of Maxwell equations with localized sources modeled as dipoles. We establish the uniqueness of the minimizer of the criterion for general geometries and the uniqueness of its critical point for the Euclidean geometry, that is when the boundary is a plane. This has consequences on the numerical approach, for the convergence of the computed solution to the global minimizer. Related inverse potential problems have applications in biomedical imaging issues pertaining to neurosciences, and in paleomagnetism issues pertaining to geosciences. There, solutions to such inverse problems are used to recover electric currents in the brain, or rock magnetizations, from measurements of the induced electric potential or magnetic field.</p>","PeriodicalId":49088,"journal":{"name":"Computational Methods and Function Theory","volume":"40 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140570217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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