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For u ∉ Q̄ with uū algebraic and distinct non-zero algebraic a₁, a₂, the space Q̄ + Q̄u + Q̄ū + Q̄u/(u² − a₁) + Q̄u/(u² − a₂) carries a 2×3 configuration

Proved
DiazModulus.circle_point_two_pole_extension_carries_two_by_three_configuration

by carlok · Oct 9, 2026 · Mathlib 0df444a (Lean v4.33.1)

diaz-modulus-leannumber-theorytranscendence

Let u∈C∖Q‾u \in \mathbb{C} \setminus \overline{\mathbb{Q}}u∈C∖Q​ with ρ=uuˉ\rho = u\bar uρ=uuˉ algebraic, let a1≠a2a_1 \neq a_2a1​=a2​ be non-zero algebraic numbers, zi=u/(u2−ai)z_i = u/(u^2 - a_i)zi​=u/(u2−ai​), H0=Q‾+Q‾u+Q‾uˉH_0 = \overline{\mathbb{Q}} + \overline{\mathbb{Q}}u + \overline{\mathbb{Q}}\bar uH0​=Q​+Q​u+Q​uˉ and W=H0+Q‾z1+Q‾z2W = H_0 + \overline{\mathbb{Q}}z_1 + \overline{\mathbb{Q}}z_2W=H0​+Q​z1​+Q​z2​. Then there are x1,x2x_1, x_2x1​,x2​, linearly independent over Q‾\overline{\mathbb{Q}}Q​, and y1,y2,y3y_1, y_2, y_3y1​,y2​,y3​, linearly independent over Q‾\overline{\mathbb{Q}}Q​, with all six products xiyjx_iy_jxi​yj​ in WWW.

The configuration is x=(1,u2)x = (1, u^2)x=(1,u2), y=(b,bu2,bu4)y = (b, bu^2, bu^4)y=(b,bu2,bu4), b=1/(u(u2−a1)(u2−a2))b = 1/(u(u^2 - a_1)(u^2 - a_2))b=1/(u(u2−a1​)(u2−a2​)): WWW contains the progression b,bu2,bu4,bu6b, bu^2, bu^4, bu^6b,bu2,bu4,bu6. For a2=ρ2/aˉ1a_2 = \rho^2/\bar a_1a2​=ρ2/aˉ1​ this is the first family of DiazModulus.circle_point_conjugate_pair_extension_carries_two_by_three_configuration; no conjugation condition is needed here.

Proof. Take x=(1,u2)x = (1, u^2)x=(1,u2) and y=(b,bu2,bu4)y = (b, bu^2, bu^4)y=(b,bu2,bu4) with b=1/(u(u2−a1)(u2−a2))b = 1/(u(u^2 - a_1)(u^2 - a_2))b=1/(u(u2−a1​)(u2−a2​)). The six products are b,bu2,bu4,bu6b, bu^2, bu^4, bu^6b,bu2,bu4,bu6, each in WWW by partial fractions, using u−1=uˉ/ρu^{-1} = \bar u/\rhou−1=uˉ/ρ: b=(a1a2)−1u−1+(a1(a1−a2))−1z1+(a2(a2−a1))−1z2b = (a_1a_2)^{-1}u^{-1} + (a_1(a_1 - a_2))^{-1}z_1 + (a_2(a_2 - a_1))^{-1}z_2b=(a1​a2​)−1u−1+(a1​(a1​−a2​))−1z1​+(a2​(a2​−a1​))−1z2​, bu2=(z1−z2)/(a1−a2)bu^2 = (z_1 - z_2)/(a_1 - a_2)bu2=(z1​−z2​)/(a1​−a2​), bu4=(a1z1−a2z2)/(a1−a2)bu^4 = (a_1z_1 - a_2z_2)/(a_1 - a_2)bu4=(a1​z1​−a2​z2​)/(a1​−a2​), bu6=u+(a12z1−a22z2)/(a1−a2)bu^6 = u + (a_1^2z_1 - a_2^2z_2)/(a_1 - a_2)bu6=u+(a12​z1​−a22​z2​)/(a1​−a2​). Both families are free because uuu is transcendental over Q‾\overline{\mathbb{Q}}Q​.

Novelty. Not asserted for the shape: it is the progression of Fischler (2001, Lemma 6.1) and Diaz (2007, Th. 7(2)), with ratio u2u^2u2.

Preamble
import Definitions.Def_DiazModulus
Formal statement
open Complex ComplexConjugate

namespace DiazModulus

theorem circle_point_two_pole_extension_carries_two_by_three_configuration (u a₁ a₂ : ℂ)
    (hu : u ∉ Qbar) (hρ : IsAlgebraic ℚ (u * conj u)) (ha₁ : a₁ ∈ Qbar) (ha₂ : a₂ ∈ Qbar)
    (ha₁0 : a₁ ≠ 0) (ha₂0 : a₂ ≠ 0) (ha : a₁ ≠ a₂) :
    ∃ (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, u / (u ^ 2 - a₁), u / (u ^ 2 - a₂)} : Set ℂ) := by
  sorry

end DiazModulus
Source
The configuration is the progression of S. Fischler, Orbits under algebraic groups and logarithms of algebraic numbers, Acta Arith. 100 (2001), 167–187, Lemma 6.1 (p. 184), repeated in G. Diaz, Produits et quotients de combinaisons linéaires de logarithmes de nombres algébriques : conjectures et résultats partiels, J. Théor. Nombres Bordeaux 19 (2007), 373–391, Th. 7(2) (p. 390), with ratio u². R7 of the Diaz modulus mission. Formal proof: Diaz modulus mission, 9 October 2026 (C. Perassi).

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