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Quasiconformal Extension of Meromorphic Functions with High-Order Poles

Complex Variables 2025-11-13 v1

Abstract

In this paper, we study the class Σ(m)(p){\Sigma^{(m)}(p)} of meromorphic univalent functions ff in D\mathbb{D} with a pole of order m1{m \geq 1} at p(0,1)p \in (0,1), admitting a kk-quasiconformal extension (0k<10 \leq k < 1) to C^\widehat{\mathbb{C}}. Using the Area Theorem and convolution methods, we establish a generalized area-type inequality and derive explicit analytic membership conditions for Σ(m)(p)\Sigma^{(m)}(p). We also extend the convolution theorem to a modified Hadamard product of mm functions, fjΣkj(m)(p)f_j \in \Sigma^{(m)}_{k_j}(p), determining sufficient conditions for the product to be in Σα(m)(p){\Sigma^{(m)}_{\alpha}(p)}, with α\alpha defined by kjk_j and pp. Further results include a sufficient criterion for sense-preserving harmonic mappings on convex domains to admit quasiconformal extensions, and the sharp Schwarzian norm for fΣk(p)f \in \Sigma_k(p) (the m=1m=1 case). These findings improve upon existing results of [{\em Proc. Amer. Math. Soc.}, {144}(6) (2016), 2593--2601].

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Cite

@article{arxiv.2511.09121,
  title  = {Quasiconformal Extension of Meromorphic Functions with High-Order Poles},
  author = {Molla Basir Ahamed and Partha Pratim Roy},
  journal= {arXiv preprint arXiv:2511.09121},
  year   = {2025}
}

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16 pages