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Lowener Theory on Analytic Universal Covering Maps

Complex Variables 2025-11-12 v2

Abstract

We study Loewner chains in H0(D)\mathcal{H}_0(\mathbb{D}) without assuming univalence of each element. We prove a decomposition: every chain admits a factorization ft=Fgtf_t=F\circ g_t, where FF is analytic on D(0,r)\mathbb{D}(0,r) with r=limtsupIft(0)r=\lim_{t \nearrow \sup I} f_t'(0), and {gt}\{g_t\} is a classical Loewner chain of univalent functions. Under a mild regularity assumption on tft(0)t \mapsto f_t'(0), we derive a partial differential equation that generalizes the Loewner--Kufarev equation. We then develop a Loewner theory for chains of universal covering maps. We characterize such chains in terms of domain families {Ωt}\{\Omega_t\}: continuity and monotonicity of {ft}\{f_t\} are equivalent to kernel continuity and monotonicity of {Ωt}\{\Omega_t\}. We further show that the connectivity C(Ωt)=#(C^Ωt)C(\Omega_t)=\#(\hat{\mathbb{C}}\setminus \Omega_t) is a left-continuous nondecreasing function of tt. Building on these results, we formulate a Loewner theory on Fuchsian groups and obtain evolution equations for deck transformations. As an application, we study hyperbolic metrics and establish a formula for the logarithmic derivative of the hyperbolic density along the chain. Our results provide a unified framework linking classical Loewner theory, covering maps, and the geometry of hyperbolic domains.

Keywords

Cite

@article{arxiv.1907.11987,
  title  = {Lowener Theory on Analytic Universal Covering Maps},
  author = {Hiroshi Yanagihara},
  journal= {arXiv preprint arXiv:1907.11987},
  year   = {2025}
}

Comments

65 pages

R2 v1 2026-06-23T10:32:51.228Z