Flat Littlewood polynomials exist
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Problem statement
Notes: Unavailable.
Source: P. Balister, B. Bollobás, R. Morris, J. Sahasrabudhe, and M. Tiba, `Flat Littlewood polynomials exist`, Annals of Math, 192 (3) 2020. Statement taken from https://github.com/ImperialCollegeLondon/AnnalsChallenge (v1.0.0, e32eb14), AnnalsChallenge/AnnalsOfMathematics/2020-192-3-FlatLittlewoodPoly.lean
Informal solution: Unavailable.
theorem theorem_1_1 :
∃ Δ δ : ℝ, Δ > δ ∧ δ > 0 ∧ ∀ n ≥ 2,
∃ P : ℂ[X], FlatLittlewoodPoly.IsLittlewoodPolynomial P ∧ P.natDegree = n ∧
∀ z : ℂ, ‖z‖ = 1 → δ * √n ≤ ‖P.eval z‖ ∧
‖P.eval z‖ ≤ Δ * √n := ⊢ ∃ Δ δ,
Δ > δ ∧
δ > 0 ∧
∀ n ≥ 2,
∃ P,
IsLittlewoodPolynomial P ∧
P.natDegree = n ∧ ∀ (z : ℂ), ‖z‖ = 1 → δ * √↑n ≤ ‖Polynomial.eval z P‖ ∧ ‖Polynomial.eval z P‖ ≤ Δ * √↑n
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