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For u ∉ Q̄, Q̄u⁻¹ + Q̄ + Q̄u + Q̄u³ + Q̄u⁴ is spanned by the products of (1, u) and (u⁻¹, 1, u³), and contains none of u², u⁻², 1/(u − b)

Proved
DiazModulus.laurent_case_two_configuration_invisible

by carlok · Oct 10, 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​ and V=Q‾u−1+Q‾+Q‾u+Q‾u3+Q‾u4V = \overline{\mathbb{Q}}u^{-1} + \overline{\mathbb{Q}} + \overline{\mathbb{Q}}u + \overline{\mathbb{Q}}u^3 + \overline{\mathbb{Q}}u^4V=Q​u−1+Q​+Q​u+Q​u3+Q​u4. Then (1,u)(1, u)(1,u) and (u−1,1,u3)(u^{-1}, 1, u^3)(u−1,1,u3) are free over Q‾\overline{\mathbb{Q}}Q​, their six products span VVV, and VVV contains none of u2u^2u2, u−2u^{-2}u−2 and 1/(u−b)1/(u - b)1/(u−b) (b∈Q‾b \in \overline{\mathbb{Q}}b∈Q​ non-zero).

So VVV carries a 2×32 \times 32×3 configuration whose products fill the whole five-dimensional space (the second case of the classification, not a geometric progression), and no four-dimensional H0+Q‾w⊆VH_0 + \overline{\mathbb{Q}}w \subseteq VH0​+Q​w⊆V is one of Theorem B's. VVV is not stable under conjugation, so it says nothing at a candidate; it shows that the conjugation condition is needed in the conjecture that every such space is either visible to Theorem B or contains a progression.

Proof. Distinct powers of the transcendental uuu are free, so (1,u)(1, u)(1,u) and (u−1,1,u3)(u^{-1}, 1, u^3)(u−1,1,u3) are free; the six products are u−1,1,u3,1,u,u4u^{-1}, 1, u^3, 1, u, u^4u−1,1,u3,1,u,u4. A membership of u2u^2u2, u−2u^{-2}u−2 or 1/(u−b)1/(u - b)1/(u−b) in the span of u−1,1,u,u3,u4u^{-1}, 1, u, u^3, u^4u−1,1,u,u3,u4 clears to a polynomial identity: for u2u^2u2 the coefficient of X3X^3X3 is −1-1−1, for u−2u^{-2}u−2 the constant term is 111, and for 1/(u−b)1/(u - b)1/(u−b) the identity u=(u−b)P(u)u = (u - b)P(u)u=(u−b)P(u) fails at b≠0b \neq 0b=0.

Novelty. Not found in the sources read; it is short.

Preamble
import Definitions.Def_DiazModulus
Formal statement
open Complex ComplexConjugate

namespace DiazModulus

theorem laurent_case_two_configuration_invisible (u : ℂ) (hu : u ∉ Qbar) :
    LinearIndependent (↥Qbar) ![1, u] ∧ LinearIndependent (↥Qbar) ![u⁻¹, 1, u ^ 3] ∧
      Submodule.span Qbar (Set.range fun ij : Fin 2 × Fin 3 => ![1, u] ij.1 * ![u⁻¹, 1, u ^ 3] ij.2) = Submodule.span Qbar ({u⁻¹, 1, u, u ^ 3, u ^ 4} : Set ℂ) ∧
      u ^ 2 ∉ Submodule.span Qbar ({u⁻¹, 1, u, u ^ 3, u ^ 4} : Set ℂ) ∧ (u ^ 2)⁻¹ ∉ Submodule.span Qbar ({u⁻¹, 1, u, u ^ 3, u ^ 4} : Set ℂ) ∧
      ∀ b ∈ Qbar, b ≠ 0 → (u - b)⁻¹ ∉ Submodule.span Qbar ({u⁻¹, 1, u, u ^ 3, u ^ 4} : Set ℂ) := by
  sorry

end DiazModulus
Source
Not found in the sources read. R9 of the Diaz modulus mission. Formal proof: Diaz modulus mission, 10 October 2026 (C. Perassi).

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