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On the Coefficients of Certain Subclasses of Harmonic Univalent Mappings with Nonzero Pole
Bulletin of the Brazilian Mathematical Society, New Series ( IF 0.7 ) Pub Date : 2021-02-09 , DOI: 10.1007/s00574-021-00244-x
Bappaditya Bhowmik , Santana Majee

Let Co(p), \(p\in (0,1]\) be the class of all meromorphic univalent functions \(\varphi \) defined in the open unit disc \({\mathbb {D}}\) with normalizations \(\varphi (0)=0=\varphi '(0)-1\) and having simple pole at \(z=p\in (0,1]\) such that the complement of \(\varphi ({\mathbb {D}})\) is a convex domain. The class Co(p) is called the class of concave univalent functions. Let \(S_{H}^{0}(p)\) be the class of all sense preserving univalent harmonic mappings f defined on \({\mathbb {D}}\) having simple pole at \(z=p\in (0,1)\) with the normalizations \(f(0)=f_{z}(0)-1=0\) and \(f_{\bar{z}}(0)=0\). We first derive the exact regions of variability for the second Taylor coefficients of h where \(f=h+\overline{g}\in S_{H}^{0}(p)\) with \(h-g\in Co(p)\). Next we consider the class \(S_{H}^{0}(1)\) of all sense preserving univalent harmonic mappings f in \({\mathbb {D}}\) having simple pole at \(z=1\) with the same normalizations as above. We derive exact regions of variability for the coefficients of h where \(f=h+\overline{g}\in S_{H}^{0}(1)\) satisfying \(h-e^{2i\theta }g\in Co(1)\) with dilatation \(g'(z)/h'(z)=e^{-2i\theta }z\), for some \(\theta \), \(0\le \theta <\pi \).



中文翻译:

具有非零极点的调和单调映射的某些子类的系数

p),\(P \在(0,1] \)是该类的所有亚纯单叶函数\(\ varphi \)在打开的单元盘定义\({\ mathbb {d}} \)与归一化\(\ varphi(0)= 0 = \ varphi'(0)-1 \)并在\(z = p \ in(0,1] \)处具有简单极点,使得\(\ varphi( {\ mathbb {D}})\)是一个凸域,类Cop)被称为凹单价函数类,令\(S_ {H} ^ {0}(p)\)为凸类。所有在\({\ mathbb {D}} \)上定义的保留单价谐波映射f\(z = p \ in(0,1)\)处具有简单极点,归一化为\ {f(0)= f_ {z}(0)-1 = 0 \)\(f _ {\ bar {z }}(0)= 0 \)。我们首先导出h的第二个泰勒系数的可变性的确切区域,其中\(f = h + \ overline {g} \ in S_ {H} ^ {0}(p)\)\(hg \ in Co(p )\)。下一步,我们考虑类\(S_ {H} ^ {0}(1)\)的所有感测保存单叶调和映射˚F\({\ mathbb {d}} \)具有简单的极\(Z = 1 \ ),具有与上述相同的规格化。我们得出h系数的确切可变性区域,其中\(f = h + \ overline {g} \在S_ {H} ^ {0}(1)\)中满足\(he ^ {2i \ theta} g \在Co(1)\)中满足\(g' (z)/ h'(z)= e ^ {-2i \ theta} z \),对于某些\(\ theta \)\(0 \ le \ theta <\ pi \)

更新日期:2021-02-09
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