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)
ProvedDiazModulus.laurent_case_two_configuration_invisibleLet and . Then and are free over , their six products span , and contains none of , and ( non-zero).
So carries a configuration whose products fill the whole five-dimensional space (the second case of the classification, not a geometric progression), and no four-dimensional is one of Theorem B's. 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 are free, so and are free; the six products are . A membership of , or in the span of clears to a polynomial identity: for the coefficient of is , for the constant term is , and for the identity fails at .
Novelty. Not found in the sources read; it is short.
import Definitions.Def_DiazModulus
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