Translation and residue-block assembly for the singular local plane-curve determinant theorem.
theorem
CCDN.singular_plane_chart_det_divisibility_mod
{p μ s : ℕ}
[Fact (Nat.Prime p)]
(f : MvPolynomial (Fin 2) ℤ)
(F : Fin s → MvPolynomial (Fin 2) ℤ)
(x : Fin s → Fin 2 → ℤ)
(a : Fin 2 → ℤ)
(hf : (MvPolynomial.map (Int.castRingHom (ZMod p))) ((originShift a) f) ∈ MvPolynomial.idealOfVars (Fin 2) (ZMod p) ^ μ)
(hμ : (MvPolynomial.homogeneousComponent μ) ((MvPolynomial.map (Int.castRingHom (ZMod p))) ((originShift a) f)) ≠ 0)
(hx : ∀ (i : Fin s) (j : Fin 2), ↑p ∣ x i j - a j)
(hfx : ∀ (i : Fin s), ↑p ^ multiplicityExponent s μ ∣ (MvPolynomial.eval (x i)) f)
:
↑p ^ multiplicityExponent s μ ∣ (Matrix.of fun (i j : Fin s) => (MvPolynomial.eval (x i)) (F j)).det
Singular local divisibility at an arbitrary integral representative of a residue point; multiplicity is measured on the translated reduction.
theorem
CCDN.singular_plane_residue_minorGcd
{p c s N : ℕ}
[Fact (Nat.Prime p)]
(f : MvPolynomial (Fin 2) ℤ)
(F : Fin N → MvPolynomial (Fin 2) ℤ)
(x : Fin s → Fin 2 → ℤ)
(label : Fin s → Fin c)
(a : Fin c → Fin 2 → ℤ)
(μ : Fin c → ℕ)
(hf :
∀ (i : Fin c),
(MvPolynomial.map (Int.castRingHom (ZMod p))) ((originShift (a i)) f) ∈ MvPolynomial.idealOfVars (Fin 2) (ZMod p) ^ μ i)
(hμ :
∀ (i : Fin c),
(MvPolynomial.homogeneousComponent (μ i)) ((MvPolynomial.map (Int.castRingHom (ZMod p))) ((originShift (a i)) f)) ≠ 0)
(hx : ∀ (i : Fin s) (j : Fin 2), ↑p ∣ x i j - a (label i) j)
(hfx : ∀ (i : Fin s), (MvPolynomial.eval (x i)) f = 0)
:
↑p ^ ∑ i : Fin c, multiplicityExponent (Fintype.card { k : Fin s // label k = i }) (μ i) ∣ Int.Matrix.minorGcd (Matrix.of fun (i : Fin s) (j : Fin N) => (MvPolynomial.eval (x i)) (F j))
Summed multiplicity exponents for arbitrary residue blocks, including singular blocks. Each local hypothesis describes the reduced equation.