Module

GluingData.lean

Nyll.SchemeTheory.WeilRestriction.GluingData
4 declarations indexed from sourceView source ↗

Gluing data from local relative representers

Local representations of one presheaf on Over S determine relative gluing data on a locally directed open cover. The transition maps and cartesian squares are constructed from universal elements, using the iterated slice equivalence to work in Over S throughout.

The resulting glued scheme is finite étale if each local representer is. Its global representing property is a separate sheaf-descent step.

Declarations

SchemeTheory.WeilRestriction.localRepresenterGluingData

Construct all the transition maps and pullback squares for local representers.

Source context 6 commands

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

@[expose] public section
open CategoryTheory CategoryTheory.Limits AlgebraicGeometry
noncomputable section
universe u v
namespace SchemeTheory.WeilRestriction
variable {S : Scheme.{u}} (F : (Over S)ᵒᵖ ⥤ Type u)
  (𝒰 : S.OpenCover) [Category.{v} 𝒰.I₀] [𝒰.LocallyDirected]
  (W : ∀ i : 𝒰.I₀, Over (𝒰.X i))
  (h : ∀ i : 𝒰.I₀, ((Over.map (𝒰.f i)).op ⋙ F).RepresentableBy (W i))
def localRepresenterGluingData : 𝒰.RelativeGluingData
SchemeTheory.WeilRestriction.localRepresenterGluingData_app

The local structure maps of the constructed gluing data are the given ones.

Source context 6 commands

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

@[expose] public section
open CategoryTheory CategoryTheory.Limits AlgebraicGeometry
noncomputable section
universe u v
namespace SchemeTheory.WeilRestriction
variable {S : Scheme.{u}} (F : (Over S)ᵒᵖ ⥤ Type u)
  (𝒰 : S.OpenCover) [Category.{v} 𝒰.I₀] [𝒰.LocallyDirected]
  (W : ∀ i : 𝒰.I₀, Over (𝒰.X i))
  (h : ∀ i : 𝒰.I₀, ((Over.map (𝒰.f i)).op ⋙ F).RepresentableBy (W i))
lemma localRepresenterGluingData_app (i : 𝒰.I₀) :
    (localRepresenterGluingData F 𝒰 W h).natTrans.app i = (W i).hom
SchemeTheory.WeilRestriction.gluedLocalRepresenter

The scheme obtained by gluing the local representers, with its map to the base.

Source context 7 commands

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

@[expose] public section
open CategoryTheory CategoryTheory.Limits AlgebraicGeometry
noncomputable section
universe u v
namespace SchemeTheory.WeilRestriction
variable {S : Scheme.{u}} (F : (Over S)ᵒᵖ ⥤ Type u)
  (𝒰 : S.OpenCover) [Category.{v} 𝒰.I₀] [𝒰.LocallyDirected]
  (W : ∀ i : 𝒰.I₀, Over (𝒰.X i))
  (h : ∀ i : 𝒰.I₀, ((Over.map (𝒰.f i)).op ⋙ F).RepresentableBy (W i))
variable [Quiver.IsThin 𝒰.I₀] [Small.{u} 𝒰.I₀]
def gluedLocalRepresenter : Over S
SchemeTheory.WeilRestriction.gluedLocalRepresenter_isFiniteEtale

Finite étaleness of the local representers descends to their glued scheme.

Source context 7 commands

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

@[expose] public section
open CategoryTheory CategoryTheory.Limits AlgebraicGeometry
noncomputable section
universe u v
namespace SchemeTheory.WeilRestriction
variable {S : Scheme.{u}} (F : (Over S)ᵒᵖ ⥤ Type u)
  (𝒰 : S.OpenCover) [Category.{v} 𝒰.I₀] [𝒰.LocallyDirected]
  (W : ∀ i : 𝒰.I₀, Over (𝒰.X i))
  (h : ∀ i : 𝒰.I₀, ((Over.map (𝒰.f i)).op ⋙ F).RepresentableBy (W i))
variable [Quiver.IsThin 𝒰.I₀] [Small.{u} 𝒰.I₀]
lemma gluedLocalRepresenter_isFiniteEtale
    (hFinite : ∀ i : 𝒰.I₀, IsFiniteEtale (W i).hom) :
    IsFiniteEtale (gluedLocalRepresenter F 𝒰 W h).hom