Exact-rank Bombieri--Vaaler comparison for higher-dimensional hypersurfaces. Absence of an auxiliary polynomial forces the explicit numerical inequality.
theorem
CCDN.hypersurface_homogeneous_rank_pos
{n d M s : ℕ}
(hd : 0 < d)
(hdM : d ≤ M)
(hr : s + (n + 2 + (M - d)).choose (M - d) = (n + 2 + M).choose M)
:
The Hilbert function s of a degree-d hypersurface in n + 3 variables, defined by
s + C(n + 2 + (M - d), M - d) = C(n + 2 + M, M), is positive in every degree M ≥ d.
theorem
CCDN.hypersurface_no_auxiliary_height_comparison
{K : Type u_1}
[Field K]
[CharZero K]
[IsAlgClosed K]
{n d M t : ℕ}
(order : MonomialOrder (Fin (n + 3)))
(f : MvPolynomial (Fin (n + 3)) ℤ)
(hf : f.IsHomogeneous d)
(hd : 0 < d)
(hdM : d ≤ M)
(hir : Irreducible ((MvPolynomial.map (Int.castRingHom K)) f))
(H : ℝ)
(hH : 1 ≤ H)
(hcoeff : CoefficientHeightLE f H)
{B : ℝ}
{z : Fin t → IntPoint (n + 3)}
(hzB : IsPrimitiveBoxZeroFamily f B z)
(hrel :
∀ (g : MvPolynomial (Fin (n + 3)) ℤ), g.IsHomogeneous M → (∀ (i : Fin t), (MvPolynomial.eval (z i)) g = 0) → f ∣ g)
:
∃ (s : ℕ),
0 < s ∧ s + (n + 2 + (M - d)).choose (M - d) = (n + 2 + M).choose M ∧ ↑(n + 1).factorial ^ (1 / (↑n + 1)) / (↑n + 2) * ↑s ^ (1 + 1 / (↑n + 1)) * (Real.log ↑s - (↑n + 1) * (4 * Real.log ↑d + Real.log (1 + Real.log H / ↑d ^ 2)) - hypersurfaceHeightDeterminantError n) ≤ Real.log ↑s.factorial / 2 + ↑s / 2 * Real.log ↑((n + 2 + M).choose M) + ↑s * ↑M * Real.log B - (↑((n + 2 + M).choose M) - ↑s) * Real.log |↑(order.leadingCoeff f)|
With no auxiliary nonmultiple of degree M, the exact homogeneous Hilbert rank satisfies the archimedean/nonarchimedean determinant comparison.