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Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.

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Claim. Let f(z)=∏ν=1n(z−zν)f(z)=\prod_{\nu=1}^n(z-z_\nu) with every ∣zν∣≤1\lvert z_\nu\rvert\le1. Theorem 4 of Pommerenke, On metric properties of complex polynomials, Michigan Math. J. 8 (1961), no. 2, 97–115 (printed p. 101), states that the set E={z:∣f(z)∣≤1}E=\{z:\lvert f(z)\rvert\le1\} contains a disk of radius (2e)−1n−2(2e)^{-1}n^{-2}; the proof centers the disk at a zero of ff and places it in the component of EE through 00. Every point of the open disk has ∣f∣<1\lvert f\rvert<1, so in the notation of Problem 1039

ρ(f)≥12en2\rho(f)\ge\frac{1}{2en^2}

for every such ff, and the minimal inradius ρn=inf⁡deg⁡f=nρ(f)\rho_n=\inf_{\deg f=n}\rho(f) is at least 1/(2en2)1/(2en^2). The paper introduces the theorem by recalling the question of Erdős, Herzog and Piranian whether $\rho\ge\mathrm{const}\cdot n^{-1}$ when the zeros lie in the closed unit disk, their Problem 3, and says that it proves only a weaker estimate. The proof combines the diameter bound of the paper's Theorem 3 for the component through 00, hence a capacity above 1/41/4, with the author's derivative bound ∣f′∣<2en2\lvert f'\rvert<2en^2 on that component, and integrates from a zero to the nearest boundary point. The theorem is recorded on the result page Theorem 4 of the card Pommerenke 1961.

Covers. The lower bound ρn≥1/(2en2)\rho_n\ge1/(2en^2). It settles neither the order of ρn\rho_n nor the second question, whether ρn≫1/n\rho_n\gg1/n; the bound was improved to order 1/(nlog⁡n)1/(n\sqrt{\log n}) on Krishnapur, Lundberg and Ramachandran 2025, and the order 1/n1/n is the claim on Price 2026.

Depends on. No page of this wiki: the proof is self-contained in the paper, with the external inputs the result page names.

Acceptance. Refereed: the paper appeared in the Michigan Mathematical Journal in 1961 (volume 8, issue 2; the issue carries no month, so the page is dated to the first day of the publication year). The site's commentary credits the bound to this paper, cited as [Po61], but labels the problem OPEN, so the remark is not acceptance and no reviewed is listed. Nothing here rests on this project's own review.