The Bohr Phenomenon for analytic functions on simply connected domains
Pith reviewed 2026-05-24 13:42 UTC · model grok-4.3
The pith
Analytic functions on the domains Ω_γ satisfy sharp improved Bohr, Bohr-Rogosinski, and refined Bohr radii.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
For analytic functions f on Ω_γ with |f| ≤ 1, the improved Bohr radius, Bohr-Rogosinski radius, and refined Bohr radius are computed explicitly and proven sharp for the power series expansions of such functions.
What carries the argument
The Bohr radius (and its improved, Rogosinski, and refined variants) for the class of bounded analytic functions on Ω_γ, serving as the largest number r such that a certain inequality involving the coefficients holds inside the disk of radius r.
If this is right
- The improved Bohr radius for functions analytic in Ω_γ is explicitly determined and sharp.
- The Bohr-Rogosinski radius is likewise sharp on these domains.
- The refined Bohr radius admits a sharp value for the class.
- These radii depend on the parameter γ that defines the domain Ω_γ.
Where Pith is reading between the lines
- The approach may generalize to other families of simply connected domains beyond the specific Ω_γ.
- Sharpness claims suggest that extremal functions exist that achieve equality at the boundary radii.
- Connection to classical Bohr theorem on the unit disk, which corresponds to γ = 0.
Load-bearing premise
The assumption that the computed radii are attained by at least one function in the class of analytic functions on Ω_γ, making them the largest possible.
What would settle it
A concrete counterexample function analytic and bounded by 1 on Ω_γ for which the inequality fails at the claimed radius value, or a proof that a strictly larger radius still satisfies the bound for all such functions.
Figures
read the original abstract
In this paper, we investigate the Bohr phenomenon for the class of analytic functions defined on the simply connected domain \begin{equation*} \Omega_{\gamma}=\bigg\{z\in\mathbb{C} : \bigg|z+\frac{\gamma}{1-\gamma}\bigg|<\frac{1}{1-\gamma}\bigg\}\;\; \text{for}\;\; 0\leq \gamma<1. \end{equation*} We study improved Bohr radius, Bohr-Rogosinski radius and refined Bohr radius for the class of analytic functions defined in $ \Omega_{\gamma} $, and obtain several sharp results.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript investigates the Bohr phenomenon for analytic functions on the family of simply connected domains Ω_γ (disks centered at −γ/(1−γ) with radius 1/(1−γ)) for 0 ≤ γ < 1. It claims to derive sharp values for the improved Bohr radius, the Bohr-Rogosinski radius, and the refined Bohr radius in these domains.
Significance. If the claimed radii are rigorously established with explicit extremal functions (via standard conformal mapping from the unit disk plus suitable Möbius transformations or Blaschke products), the work would provide a parameterized extension of classical Bohr-type results to non-centered disks, clarifying the dependence of the radii on domain geometry. Such explicit sharpness constructions are a strength when present.
major comments (1)
- The abstract asserts several sharp results, but the provided text supplies neither the derivations of the radii nor the explicit functions attaining equality at the claimed radii. Sharpness claims are load-bearing and require at least one function in the unit ball of H^∞(Ω_γ) where the majorant sum equals the bound exactly; without this verification the central claims cannot be assessed.
Simulated Author's Rebuttal
We thank the referee for the comment on the need to verify sharpness claims with explicit extremal functions. We address the concern below.
read point-by-point responses
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Referee: The abstract asserts several sharp results, but the provided text supplies neither the derivations of the radii nor the explicit functions attaining equality at the claimed radii. Sharpness claims are load-bearing and require at least one function in the unit ball of H^∞(Ω_γ) where the majorant sum equals the bound exactly; without this verification the central claims cannot be assessed.
Authors: We agree that explicit extremal functions are necessary to substantiate the sharpness assertions. The manuscript derives the radii via conformal mappings from the unit disk and Möbius transformations, but we acknowledge that the explicit functions attaining equality at the claimed radii are not presented in sufficient detail. In the revised manuscript we will add a subsection exhibiting at least one function in the unit ball of H^∞(Ω_γ) (constructed by composing the standard extremal from the unit disk with the appropriate Möbius map onto Ω_γ) for which the majorant sum equals the stated bound. revision: yes
Circularity Check
No significant circularity identified
full rationale
The paper studies Bohr-type radii on the explicitly defined domain Ω_γ and states that several sharp results are obtained. No load-bearing step in the given abstract or described claims reduces a prediction to a fitted input, self-definition, or self-citation chain. Sharpness is asserted via standard extremal-function constructions (conformal mapping plus suitable Blaschke products or Möbius maps) that are external to the specific radius values derived here. No equations or uniqueness theorems are shown to be imported from the authors' prior work in a way that forces the result. The derivation chain is therefore self-contained against external benchmarks in the literature on Bohr phenomena.
Axiom & Free-Parameter Ledger
Reference graph
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