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Asymptotically minimal maxima of real Littlewood polynomials
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Abstract
We prove that the minimum possible maximum modulus on the unit circle of a polynomial with N consecutive real coefficients in $\{-1,1\}$ is $(1+o(1))\sqrt N$, as N tends to infinity through all integers. This disproves the real-sign analogue of Erdős's fixed relative-gap conjecture. As a consequence, the largest binary merit factor at length N tends to infinity through all integer lengths, disproving Turyn's conjecture.
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Notes
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Collected automatically by AI tools (Claude Opus 5.5 and GPT-6 Astra, 2026-10-21) and not checked by a person. May be wrong or incomplete. Report an error.
Comments and discussion
- Thomas Bloom, Erdős problems in the OpenAI proofs (erdosproblems.com blog, 8 October 2026). Lists Erdős Problem #1150 among the release's claimed results, links the ultraflat companion PDF and the comparator Lean file for this paper's Theorem 1.1, and notes that the 16-page PDF "appears to heavily rely on two other related PDFs". [family-level]
- Erdős Problems forum, Problem #1150 discussion thread (erdosproblems.com, comments February–August 2026). Predates the release; T. Bloom and T. Tao comment on gaps in el Abdalaoui's arXiv:2504.21499, one of the contrary nonflatness claims examined in this paper's Appendix A, and el Abdalaoui replies.
Formalization
- OpenAI math release, Lean scope notes for family 076 (release Lean docs, October 2026). Describes the formalized upper bound $(1+\eta)\sqrt N$ at all large lengths and the finite-exponent $L^p$ flatness of one all-length family, both without effective rates.
- OpenAI, AsymptoticallyMinimalLittlewood.lean (comparator statement) (openai/math, October 2026). Lean statement of Theorem 1.1; the proof is in lean/OAI/Analysis/Littlewood/Main.lean.
- OpenAI, LittlewoodFiniteFlatness.lean (comparator statement) (openai/math, October 2026). Lean statement that one family of sign vectors is $L^p$-flat for every fixed $p>0$; merit factors themselves are not defined in the Lean code.
- Google DeepMind formal-conjectures, FormalConjectures/ErdosProblems/1150.lean (formal-conjectures, 2026). Formal statement of Erdős Problem #1150, tagged as solved with answer "No", citing this paper and linking the OpenAI Lean proof; the statement in that file itself is closed by
sorry.
Related prior literature mentioned by others
- Andrew Odlyzko, Search for ultraflat polynomials with plus and minus one coefficients (in Connections in Discrete Mathematics, Cambridge University Press, 2018). Flagged by the erdosproblemaday.com review as not cited by the paper; its extensive computations suggested that ultraflat ±1 polynomials do not exist and also discuss the merit factor. [AI-generated per source]
- Paul Balister, Béla Bollobás, Robert Morris, Julian Sahasrabudhe and Marius Tiba, Flat Littlewood polynomials exist (Annals of Mathematics 192, 2020). The AI Proved What? exposition identifies this constant-factor two-sided flatness theorem as prior context for the family's stronger asymptotic claims. [family-level]
Possibly relevant literature (found by the agent, not checked)
- Jonathan Jedwab, Daniel J. Katz, Kai-Uwe Schmidt, Advances in the merit factor problem for binary sequences (arXiv:1205.0626; J. Combin. Theory Ser. A 120 (2013) 882–906). Computes asymptotic merit factors of Legendre-type and skew-symmetric families; background for the merit-factor consequence in Section 8, distinct from the cited Adv. Math. paper by the same authors.
Digests and expositions
- Patrick White with Claude, Erdős #1150: OpenAI ultraflat Littlewood, refereed (erdosproblemaday.com, 12 October 2026). Referee-style reading of the three family-076 papers by seven Claude "referee seats", which report no gap found and a local kernel replay of the release's 28-module Lean proof (axioms only
propext,Classical.choice,Quot.sound), noting that the formal proof replaces two cited combinatorial inputs and one analytic step of the paper. [AI-generated per source] [family-level] - Latent Seminar, Ultraflat Littlewood polynomials and autocorrelation (6 October 2026). Explains the three claims, the merit-factor implication, stationary phase, packing, discrepancy rounding and lower-bound refinements, explicitly limiting its review to statements and proof mechanisms. [family-level]
- AI Proved What?, Flat with signs only? Ultraflat Littlewood polynomials and merit factors (Episode 076, October 2026). Video and transcript explain the progression of the three manuscripts, quadratic-phase waves, rounding and the documented Lean scope. [AI-generated per source] [family-level]
Elsewhere
- VibeMathed: Problem record
- VibeMathed: Problem record
- Emergent Mind: family 076
Independent sites; their content is not reviewed here.
Cite
@misc{OAI:Asymptotically-minimal-maxima-of-real-Littlewood-polynomials-September-23-2026,
author = {{OpenAI}},
title = {{Asymptotically minimal maxima of real Littlewood polynomials}},
howpublished = {OpenAI Math Release preprint
\href{https://github.com/openai/math/blob/main/preprints/Asymptotically-minimal-maxima-of-real-Littlewood-polynomials-September-23-2026/paper.pdf}{OAI:Asymptotically-minimal-maxima-of-real-Littlewood-polynomials-September-23-2026}},
year = {2026}
}Lean formalization
OpenAI provides Lean files for this family: lean/docs/076.md. The Lean statements have not been checked by people against the paper's claims.
Family 076: Real ultraflat Littlewood polynomials and unbounded binary merit factors
Constructs polynomials with N consecutive coefficients in $\{-1,1\}$ whose modulus is $(1+o(1))\sqrt N$ uniformly on the entire unit circle, for every sufficiently large integer length N. Thus real Littlewood polynomials are ultraflat, including at the real endpoints. Their binary merit factors tend to infinity, disproving Turyn's bounded-merit-factor conjecture.
Other papers in this family:
- Ultraflat real Littlewood polynomials · October 5, 2026
- Nearly minimal maxima and positive minima of Littlewood polynomials · October 5, 2026