A single auxiliary polynomial for all rational points of bounded projective height, with no finite-family hypothesis.
theorem
CCDN.exists_bounded_projective_zero_family
{n d : ℕ}
(f : MvPolynomial (Fin (n + 1)) ℤ)
(hf : f.IsHomogeneous d)
(B : ℝ)
:
∃ (t : ℕ) (z : Fin t → IntPoint (n + 1)),
(∀ (i : Fin t), Finset.univ.gcd (z i) = 1) ∧ (∀ (i : Fin t), (MvPolynomial.eval (z i)) f = 0) ∧ (∀ (i : Fin t), InBox (z i) B) ∧ ∀ {M : ℕ} (g : MvPolynomial (Fin (n + 1)) ℤ),
g.IsHomogeneous M →
(∀ (i : Fin t), (MvPolynomial.eval (z i)) g = 0) →
∀ (x : ProjectivePoint n),
Projectivization.mulHeight x ≤ B →
x ∈ projectiveZeroLocus ((MvPolynomial.map (Int.castRingHom ℚ)) f) →
x ∈ projectiveZeroLocus ((MvPolynomial.map (Int.castRingHom ℚ)) g)
The rational points of height at most B on the zero locus of f, as a finite family
of bounded primitive integer zeros. A form vanishing on the family vanishes at every such
point.
theorem
CCDN.hypersurface_absolute_projective_auxiliary
{K : Type u_1}
[Field K]
[CharZero K]
[IsAlgClosed K]
{n d : ℕ}
(f : MvPolynomial (Fin (n + 3)) ℤ)
(hf : f.IsHomogeneous d)
(hd : 0 < d)
(hir : Irreducible ((MvPolynomial.map (Int.castRingHom K)) f))
{B : ℝ}
(hB : 1 ≤ B)
:
∃ (bad : Finset ℕ) (M : ℕ),
(∀ (p : ℕ), p ∈ bad ↔ stepanovThreshold d < p ∧ HypersurfaceBadReduction f p) ∧ ↑M ≤ hypersurfaceAuxiliaryDegreeBound n d B (primeSetFactor bad) ↑(integerCoefficientHeight f) ∧ ∃ (g : MvPolynomial (Fin (n + 3)) ℤ),
g ≠ 0 ∧ g.IsHomogeneous M ∧ (∀ (x : ProjectivePoint (n + 2)),
Projectivization.mulHeight x ≤ B →
x ∈ projectiveZeroLocus ((MvPolynomial.map (Int.castRingHom ℚ)) f) →
x ∈ projectiveZeroLocus ((MvPolynomial.map (Int.castRingHom ℚ)) g)) ∧ ¬f ∣ g
The full projective-height formulation of the absolutely irreducible case of CCDN Theorem 3.1.1.