Laurent hulls: for u transcendental over a subfield K of ℂ and a finite S ⊆ ℤ, span_K{u^s : s ∈ S} carries a p×q configuration iff S contains a sumset A + B with |A| = p, |B| = q
ProvedDiazModulus.laurent_hull_config_iffA configuration over a field in a -subspace is a pair and of complex numbers, each family linearly independent over , with every product in ; it is the input of Roy's strong six exponentials theorem when , , and .
Let be a subfield of and transcendental over . For a set of integers write (the Laurent hull of ). For a finite and , carries a configuration over if and only if there are with , and .
At a candidate , brings , so hypotheses on powers of put Laurent hulls inside ; this criterion says exactly when Roy's strong six exponentials theorem can refute them through those hulls. The case is DiazModulus.power_hull_strong_six_exp_configuration_iff.
Proof. If , take , ; distinct integer powers of are independent. Conversely, choose with and polynomials supported on with . The spans of the and of the have dimensions and , hence (DiazModulus.polynomial_submodule_trailing_degrees_card) exactly and orders at . For , , with a combination of the (both sides agree at ), so ; shifting the order set of gives , and the order set of is .
Novelty. Not found in the sources read. The nearest printed results are the progression lemma of Fischler (2001, Lemma 6.1) and its repetition in Diaz (2007, Th. 7(2)); the library had the single family .
import Definitions.Def_DiazModulus
open Complex ComplexConjugate
namespace DiazModulus
open Pointwise in
theorem laurent_hull_config_iff (K : Subfield ℂ) (u : ℂ) (hT : Transcendental K u)
(S : Finset ℤ) (p q : ℕ) (hp : 1 ≤ p) (hq : 1 ≤ q) :
(∃ (x : Fin p → ℂ) (y : Fin q → ℂ), LinearIndependent K x ∧ LinearIndependent K y ∧
∀ i j, x i * y j ∈ Submodule.span K ((fun s : ℤ => u ^ s) '' (S : Set ℤ))) ↔
∃ A B : Finset ℤ, A.card = p ∧ B.card = q ∧ A + B ⊆ S := by
sorry
end DiazModulus