Module

FunctionFieldResidueAtSourceGeneric.lean

Nyll.EtaleFundamentalGroups.GaloisCovers.FunctionFieldResidueAtSourceGeneric
2 declarations indexed from sourceView source ↗

Function fields at the image of a source generic point

For a dense morphism of integral schemes, the function field of the target is canonically the residue field at the image of the source generic point. The resulting equivalence is compatible with the residue-field map to the source generic point.

Declarations

AlgebraicGeometry.Scheme.Hom.functionFieldResidueFieldRingEquivAtSourceGeneric

The target function field, identified with the residue field at the image of the source generic point of a dense morphism.

Source context 6 commands

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

noncomputable section
open CategoryTheory TopologicalSpace
open AlgebraicGeometry
namespace AlgebraicGeometry.Scheme.Hom
universe u
variable {X Z : Scheme.{u}}
def functionFieldResidueFieldRingEquivAtSourceGeneric
    [IsIntegral X] [IsIntegral Z]
    (g : Z ⟶ X) (hg : DenseRange g) :
    X.functionField ≃+* X.residueField (g (genericPoint Z))
AlgebraicGeometry.Scheme.Hom.functionFieldResidueFieldRingEquivAtSourceGeneric_naturality

Naturality of the source-generic-point function-field identification.

Source context 6 commands

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

noncomputable section
open CategoryTheory TopologicalSpace
open AlgebraicGeometry
namespace AlgebraicGeometry.Scheme.Hom
universe u
variable {X Z : Scheme.{u}}
theorem functionFieldResidueFieldRingEquivAtSourceGeneric_naturality
    [IsIntegral X] [IsIntegral Z]
    (g : Z ⟶ X) (hg : DenseRange g) :
    CommRingCat.ofHom
        (g.functionFieldResidueFieldRingEquivAtSourceGeneric hg).toRingHom ≫
      g.residueFieldMap (genericPoint Z) =
    CommRingCat.ofHom (g.functionFieldMap hg) ≫
      CommRingCat.ofHom
        (Scheme.functionFieldResidueFieldRingEquiv Z).toRingHom