A Counterexample to the Area Inequality for Geometric Means of Exterior Univalent Functions
Manuscript 25 October 2026 · Online 25 October 2026
Abstract
A question of D. K. Thomas, recorded as Problem 6.50 in Hayman and Lingham's Research Problems in Function Theory, asks whether geometric means of normalized exterior univalent functions satisfy the area-theorem coefficient inequality. We give an explicit counterexample at exponent 1/2. The two factors are odd, zero-free and univalent on |z|>1, and their normalized geometric mean is analytic throughout that domain. Its first four nonzero negative Laurent coefficients have weighted squared sum 269463/262144>1. A fixed radial dilation by 1001/1000 gives factors and a mean analytic across the unit circle, with full coefficient sum finite and greater than 101/100. The proof uses elementary conformal maps and exact rational arithmetic. This gives a negative answer to the entire single-question frozen UnsolvedMath record AMR-022-6050. The package includes the complete four-page proof, exact and symbolic checks, and a source/scope audit. AI-assisted self-audited preprint; no independent peer review, formal verification or absolute-priority certification is claimed.
Record
- Affiliation
- Mercury Software GmbH
- Contact
- [email protected] · GitHub
- Result
- Complete counterexample
- Categories
- math.CV
- Manuscript
- 25 October 2026
- Online release
- 25 October 2026
- Version
- 1.0
- License
- Creative Commons Attribution 4.0 International
Files and verification
The PDF is the canonical reading copy. The source archive contains the LaTeX manuscript, bibliography, reproducibility material, and audit documents without build artefacts.
Citation
Alper Ferudun, “A Counterexample to the Area Inequality for Geometric Means of Exterior Univalent Functions,” EulerSolve Research Papers, AMR-022-6050, 2026. https://doi.org/10.5281/zenodo.23649631.
BibTeX
@misc{ferudun2026geometricarea,
author = {Ferudun, Alper},
title = {A Counterexample to the Area Inequality for Geometric Means of Exterior Univalent Functions},
year = {2026},
howpublished = {EulerSolve Research Papers},
url = {https://eulersolve.org/papers/amr-022-6050/},
doi = {10.5281/zenodo.23649631},
note = {AMR-022-6050; unrefereed preprint}
}