An explicit bounded integer moment form avoids any prescribed finite set of nonzero directions. No separation of pairs is needed for this step.
theorem
CCDN.momentCoordinate_homogeneous
(K : Type u_1)
[Field K]
(n k : ℕ)
:
(momentCoordinate K n k).IsHomogeneous 1
The moment coordinate ∑ j, k ^ j * X j is homogeneous of degree one.
theorem
CCDN.filtration_recurrence_of_infinity_avoidance
{K : Type u_1}
{L : Type u_2}
{σ : Type u_3}
[Field K]
[Field L]
[Algebra K L]
[IsAlgClosed L]
[Finite σ]
(I : Ideal (MvPolynomial σ K))
(l : MvPolynomial σ K)
(hl : l.IsHomogeneous 1)
(hzero : ∀ z ∈ MvPolynomial.zeroLocus L (leadingInfinityIdeal I ⊔ Ideal.span {l}), z = 0)
:
∃ (N : ℕ),
∀ m ≥ N,
filteredCoordinateSpace I (m + 1) = filteredCoordinateSpace I m ⊔
Submodule.map (LinearMap.mulLeft K ((Ideal.Quotient.mk I) l)) (filteredCoordinateSpace I m)
Avoiding infinity gives the eventual recurrence of the original coordinate filtration.