Maximal standard-monomial orthants construct algebraically independent original coordinates of cardinality equal to Hilbert dimension.
theorem
CCDN.exists_hilbert_dimension_independent_coordinates
{K : Type u_1}
{σ : Type u_2}
[Field K]
[Fintype σ]
[LinearOrder σ]
(I : Ideal (MvPolynomial σ K))
(hI : I ≠ ⊤)
:
∃ (U : Set σ),
Nat.card ↑U = (filteredHilbertPolynomial I).natDegree ∧ AlgebraicIndependent K fun (i : ↑U) => (Ideal.Quotient.mk I) (MvPolynomial.X ↑i)
The independent coordinates are constructed from a maximal standard orthant, with exactly the degree of the Hilbert polynomial.