Composite Holomorphic Functions and Normal Families

We study the normality of families of holomorphic functions. We prove the following result. Let α(z),  ai(z),  i=1,2,…,p, be holomorphic functions and F a family of holomorphic functions in a domain D, P(z,w):=(w-a1(z))(w-a2(z))⋯(w-ap(z)),  p≥2. If Pw∘f(z) and Pw∘g(z) share α(z) IM for each pair f(z...

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Main Authors: Xiao Bing, Wu Qifeng, Yuan Wenjun
Format: Article
Language:English
Published: Wiley 2011-01-01
Series:Abstract and Applied Analysis
Online Access:http://dx.doi.org/10.1155/2011/373910
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author Xiao Bing
Wu Qifeng
Yuan Wenjun
author_facet Xiao Bing
Wu Qifeng
Yuan Wenjun
author_sort Xiao Bing
collection DOAJ
description We study the normality of families of holomorphic functions. We prove the following result. Let α(z),  ai(z),  i=1,2,…,p, be holomorphic functions and F a family of holomorphic functions in a domain D, P(z,w):=(w-a1(z))(w-a2(z))⋯(w-ap(z)),  p≥2. If Pw∘f(z) and Pw∘g(z) share α(z) IM for each pair f(z),  g(z)∈F and one of the following conditions holds: (1) P(z0,z)-α(z0) has at least two distinct zeros for any z0∈D; (2) there exists z0∈D such that P(z0,z)-α(z0) has only one distinct zero and α(z) is nonconstant. Assume that β0 is the zero of P(z0,z)-α(z0) and that the multiplicities l and k of zeros of f(z)-β0 and α(z)-α(z0) at z0, respectively, satisfy k≠lp, for all f(z)∈F, then F is normal in D. In particular, the result is a kind of generalization of the famous Montel's criterion. At the same time we fill a gap in the proof of Theorem 1.1 in our original paper (Wu et al., 2010).
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spelling doaj-art-9b8f1d94e6df41349eec37dfd2ca81f02025-08-20T02:18:25ZengWileyAbstract and Applied Analysis1085-33751687-04092011-01-01201110.1155/2011/373910373910Composite Holomorphic Functions and Normal FamiliesXiao Bing0Wu Qifeng1Yuan Wenjun2Department of Mathematics, Xinjiang Normal University, Urumqi 830054, ChinaShaozhou Normal College, Shaoguan University, Shaoguan 512009, ChinaSchool of Mathematics and Information Science, Guangzhou University, Guangzhou 510006, ChinaWe study the normality of families of holomorphic functions. We prove the following result. Let α(z),  ai(z),  i=1,2,…,p, be holomorphic functions and F a family of holomorphic functions in a domain D, P(z,w):=(w-a1(z))(w-a2(z))⋯(w-ap(z)),  p≥2. If Pw∘f(z) and Pw∘g(z) share α(z) IM for each pair f(z),  g(z)∈F and one of the following conditions holds: (1) P(z0,z)-α(z0) has at least two distinct zeros for any z0∈D; (2) there exists z0∈D such that P(z0,z)-α(z0) has only one distinct zero and α(z) is nonconstant. Assume that β0 is the zero of P(z0,z)-α(z0) and that the multiplicities l and k of zeros of f(z)-β0 and α(z)-α(z0) at z0, respectively, satisfy k≠lp, for all f(z)∈F, then F is normal in D. In particular, the result is a kind of generalization of the famous Montel's criterion. At the same time we fill a gap in the proof of Theorem 1.1 in our original paper (Wu et al., 2010).http://dx.doi.org/10.1155/2011/373910
spellingShingle Xiao Bing
Wu Qifeng
Yuan Wenjun
Composite Holomorphic Functions and Normal Families
Abstract and Applied Analysis
title Composite Holomorphic Functions and Normal Families
title_full Composite Holomorphic Functions and Normal Families
title_fullStr Composite Holomorphic Functions and Normal Families
title_full_unstemmed Composite Holomorphic Functions and Normal Families
title_short Composite Holomorphic Functions and Normal Families
title_sort composite holomorphic functions and normal families
url http://dx.doi.org/10.1155/2011/373910
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AT wuqifeng compositeholomorphicfunctionsandnormalfamilies
AT yuanwenjun compositeholomorphicfunctionsandnormalfamilies