For a real Laurent polynomial f in u/s of width k ≥ 3, or 2 with f(−λ̄) ≠ 0: W(λ, f) is conjugation-stable with a 2×3 configuration invisible to Theorem B
ProvedDiazModulus.laurent_real_pencil_configuration_invisible_to_four_dimensional_extensionsLet and let be real with (so ; with , conjugation acts as on coefficients). Let with , and let with , and (so is real). Let be the \overline{\mathbb{Q}}-span of , and write for , the value at (the pole of ). Suppose the five numbers are free, and that , or and . Put . Then is stable under conjugation and carries a configuration, and for no outside does carry one.
With DiazModulus.laurent_real_pencil_space_contains_square_of_root this settles visibility for Laurent : is visible exactly when and .
Proof. is real: conjugation sends to and to , so reindexing returns the sum. Then DiazModulus.conj_stable_real_pencil_space_carries_two_by_three_configuration gives conjugation stability and a configuration, and Theorem B (DiazModulus.circle_point_extension_two_by_three_configuration_iff) with exchange against DiazModulus.laurent_real_pencil_space_excludes_squares_and_reciprocals rules out every with .
Novelty. Not found in the sources read; it is short.
import Definitions.Def_DiazModulus
open Complex ComplexConjugate
namespace DiazModulus
theorem laurent_real_pencil_configuration_invisible_to_four_dimensional_extensions
(u s : ℂ) (hu : u ∉ Qbar) (hs : s ∈ Qbar) (hsr : conj s = s) (hss : s * s = u * conj u)
(lam : ℂ) (hlam : lam ∈ Qbar) (hlam1 : lam * conj lam = 1) (k : ℕ) (c : ℤ → ℂ)
(hc : ∀ j, c j ∈ Qbar) (hcs : ∀ j, c (-j) = conj (c j)) (hck : c k ≠ 0)
(hk : 3 ≤ k ∨ (k = 2 ∧ (∑ j ∈ Finset.Icc (-(k : ℤ)) k, c j * (-conj lam) ^ j) ≠ 0)) (hind : LinearIndependent (↥Qbar) ![1, u, conj u, (∑ j ∈ Finset.Icc (-(k : ℤ)) k, c j * (u / s) ^ j), (∑ j ∈ Finset.Icc (-(k : ℤ)) k, c j * (u / s) ^ j) / (s + lam * u)]) :
(∀ w ∈ Submodule.span Qbar ({1, u, conj u, (∑ j ∈ Finset.Icc (-(k : ℤ)) k, c j * (u / s) ^ j), (∑ j ∈ Finset.Icc (-(k : ℤ)) k, c j * (u / s) ^ j) / (s + lam * u)} : Set ℂ), conj w ∈ Submodule.span Qbar ({1, u, conj u, (∑ j ∈ Finset.Icc (-(k : ℤ)) k, c j * (u / s) ^ j), (∑ j ∈ Finset.Icc (-(k : ℤ)) k, c j * (u / s) ^ j) / (s + lam * u)} : Set ℂ)) ∧
(∃ (x : Fin 2 → ℂ) (y : Fin 3 → ℂ), LinearIndependent (↥Qbar) x ∧ LinearIndependent (↥Qbar) y ∧
∀ i j, x i * y j ∈ Submodule.span Qbar ({1, u, conj u, (∑ j ∈ Finset.Icc (-(k : ℤ)) k, c j * (u / s) ^ j), (∑ j ∈ Finset.Icc (-(k : ℤ)) k, c j * (u / s) ^ j) / (s + lam * u)} : Set ℂ)) ∧
∀ w ∈ Submodule.span Qbar ({1, u, conj u, (∑ j ∈ Finset.Icc (-(k : ℤ)) k, c j * (u / s) ^ j), (∑ j ∈ Finset.Icc (-(k : ℤ)) k, c j * (u / s) ^ j) / (s + lam * u)} : Set ℂ), w ∉ Submodule.span Qbar ({1, u, conj u} : Set ℂ) →
¬ ∃ (x : Fin 2 → ℂ) (y : Fin 3 → ℂ), LinearIndependent (↥Qbar) x ∧ LinearIndependent (↥Qbar) y ∧
∀ i j, x i * y j ∈ Submodule.span Qbar ({1, u, conj u, w} : Set ℂ) := by
sorry
end DiazModulus