Module

GluedComparison.lean

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

Comparing glued representers with their local pieces

The cartesian squares of relative gluing identify each local representer with the pullback of the glued scheme. The resulting hom-set equivalence has an explicit inverse: compose a local map with its gluing inclusion.

Declarations

SchemeTheory.WeilRestriction.gluedLocalRepresenterInclusion

The local representer maps to the glued scheme over the original base.

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))
  [Quiver.IsThin 𝒰.I₀] [Small.{u} 𝒰.I₀]
def gluedLocalRepresenterInclusion (i : 𝒰.I₀) :
    (Over.map (𝒰.f i)).obj (W i) ⟶ gluedLocalRepresenter F 𝒰 W h
SchemeTheory.WeilRestriction.gluedLocalRepresenterPullbackIso

Pulling the glued scheme back to a cover member recovers its local representer.

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))
  [Quiver.IsThin 𝒰.I₀] [Small.{u} 𝒰.I₀]
def gluedLocalRepresenterPullbackIso (i : 𝒰.I₀) :
    W i ≅ (Over.pullback (𝒰.f i)).obj (gluedLocalRepresenter F 𝒰 W h)
SchemeTheory.WeilRestriction.gluedLocalRepresenterHomEquiv

Maps from a test scheme over a cover member into the glued scheme are equivalent to maps into the corresponding local representer.

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))
  [Quiver.IsThin 𝒰.I₀] [Small.{u} 𝒰.I₀]
def gluedLocalRepresenterHomEquiv (i : 𝒰.I₀) (T : Over (𝒰.X i)) :
    ((Over.map (𝒰.f i)).obj T ⟶ gluedLocalRepresenter F 𝒰 W h) ≃ (T ⟶ W i)
SchemeTheory.WeilRestriction.gluedLocalRepresenterHomEquiv_symm

The inverse comparison is composition with the gluing inclusion.

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))
  [Quiver.IsThin 𝒰.I₀] [Small.{u} 𝒰.I₀]
lemma gluedLocalRepresenterHomEquiv_symm (i : 𝒰.I₀) (T : Over (𝒰.X i))
    (k : T ⟶ W i) :
    (gluedLocalRepresenterHomEquiv F 𝒰 W h i T).symm k =
      (Over.map (𝒰.f i)).map k ≫ gluedLocalRepresenterInclusion F 𝒰 W h i