Module

GenericPointNaturality.lean

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

Naturality of the actual generic point

The canonical function-field map commutes with the maps from the generic stalk spectra. This is used when comparing the actual Kummer characters on an open curve with geometric pullback from its compactification.

Declarations

AnabelianGeometry.WeightFiltration.specMap_stalk_eqToHom_comp
Source context 3 commands

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

noncomputable section
open CategoryTheory AlgebraicGeometry
namespace AnabelianGeometry.WeightFiltration
theorem specMap_stalk_eqToHom_comp
    {X : Scheme} {x y : X} (h : x = y) :
    Spec.map (eqToHom (congrArg (fun z => X.presheaf.stalk z) h)) ≫
      X.fromSpecStalk x = X.fromSpecStalk y := by
  subst y
  simp only [eqToHom_refl, Spec.map_id, Category.id_comp]
AnabelianGeometry.WeightFiltration.functionFieldMap_genericPoint

The actual generic-point square of a dominant morphism commutes.

Source context 3 commands

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

noncomputable section
open CategoryTheory AlgebraicGeometry
namespace AnabelianGeometry.WeightFiltration
theorem functionFieldMap_genericPoint
    {X Y : Scheme} [IsIntegral X] [IsIntegral Y]
    (f : Y ⟶ X) (hf : DenseRange f) :
    Spec.map (CommRingCat.ofHom (f.functionFieldMap hf)) ≫
      X.fromSpecStalk (genericPoint X) =
        Y.fromSpecStalk (genericPoint Y) ≫ f