Module

ResidueNumericalInvariants.lean

Nyll.AnabelianGeometry.WeightFiltration.ResidueNumericalInvariants
2 declarations indexed from sourceView source ↗

Recovering numerical invariants from the actual residue filtration

For an exponent greater than one, the kernel determines the genus and the image determines the size of a nonempty boundary. These are explicit numerical formulas. Recognition of the filtration from arithmetic group data is a separate theorem and is not an assumption hidden in this file.

Declarations

AnabelianGeometry.WeightFiltration.genus_eq_log_card_finiteResidue_ker

The actual residue kernel determines the genus.

Source context 5 commands

Surrounding namespaces, section variables, and local commands at this declaration.

noncomputable section
open AlgebraicGeometry CategoryTheory AlgebraicCurve NeronModelInfra
namespace AnabelianGeometry.WeightFiltration
variable {K F : Type} [Field K] [IsAlgClosed K] [CharZero K]
  [Field F] [Algebra K F] [IsCurveOver K F]
  (M : CurveModel K F)
  (ε : SchemeHomOver (𝟙 (Spec (.of K))) M.toBase)
  (n : ℕ+)
  {X : Scheme} [IsIntegral X] [CompactSpace X]
  (j : X ⟶ M.C) [IsOpenImmersion j] (hj : DenseRange j)
  (hn : IsUnit ((n : ℕ) : K))
  {Ω : Type} [Field Ω] [IsSepClosed Ω] (xi : Spec (.of Ω) ⟶ X)
include ε
theorem genus_eq_log_card_finiteResidue_ker (hn₁ : 1 < (n : ℕ)) :
    genusFF K F = Nat.log (n : ℕ)
      (Nat.card (finiteResidue M n j hj hn xi).ker) / 2
AnabelianGeometry.WeightFiltration.boundaryCard_eq_log_card_finiteResidue_range

For nonempty boundary, its cardinality is one plus the logarithm of the actual residue-image cardinality. The empty boundary is excluded explicitly.

Source context 7 commands

Surrounding namespaces, section variables, and local commands at this declaration.

noncomputable section
open AlgebraicGeometry CategoryTheory AlgebraicCurve NeronModelInfra
namespace AnabelianGeometry.WeightFiltration
variable {K F : Type} [Field K] [IsAlgClosed K] [CharZero K]
  [Field F] [Algebra K F] [IsCurveOver K F]
  (M : CurveModel K F)
  (ε : SchemeHomOver (𝟙 (Spec (.of K))) M.toBase)
  (n : ℕ+)
  {X : Scheme} [IsIntegral X] [CompactSpace X]
  (j : X ⟶ M.C) [IsOpenImmersion j] (hj : DenseRange j)
  (hn : IsUnit ((n : ℕ) : K))
  {Ω : Type} [Field Ω] [IsSepClosed Ω] (xi : Spec (.of Ω) ⟶ X)
include ε
variable [Fintype (M.openBoundaryPlaces j)]
omit [CharZero K] in
theorem boundaryCard_eq_log_card_finiteResidue_range
    (v₀ : M.openBoundaryPlaces j) (hn₁ : 1 < (n : ℕ)) :
    Fintype.card (M.openBoundaryPlaces j) =
      Nat.log (n : ℕ) (Nat.card (finiteResidue M n j hj hn xi).range) + 1