A coordinate-grid bound for a proper complete intersection. The constant depends only on the ambient dimension; the degree dependence is quadratic.
theorem
CCDN.proper_intersection_grid_card_le
{K : Type u_1}
{ι : Type u_2}
[Field K]
[Fintype ι]
{n d : ℕ}
(f g : MvPolynomial (Fin (n + 2)) K)
(hf : Prime f)
(hfg : ¬f ∣ g)
(hfd : f.totalDegree ≤ d)
(hgd : g.totalDegree ≤ d)
(S : Finset K)
(z : ι → Fin (n + 2) → K)
(hz : Function.Injective z)
(hzS : ∀ (i : ι) (j : Fin (n + 2)), z i j ∈ S)
(hzf : ∀ (i : ι), (MvPolynomial.eval (z i)) f = 0)
(hzg : ∀ (i : ι), (MvPolynomial.eval (z i)) g = 0)
:
If f is prime, g is not divisible by f, and both have total degree at most d, then the
number of distinct common zeros of f and g in the grid Sⁿ⁺² is at most (n + 2) ^ n · d² · |S| ^ n.