Module

RelativeOverlapFiniteness.lean

Nyll.SchemeTheory.FiniteEtale.RelativeOverlapFiniteness
4 declarations indexed from sourceView source ↗

Finiteness properties of actual gluing overlaps

Finite-etale models over compact open charts have compact pairwise and triple overlap objects. Their maps to the ambient quasi-separated base are quasi-compact and locally of finite type; they are not asserted to be finite over that whole base.

Declarations

AlgebraicGeometry.Scheme.Cover.relativeOverlap_compactSpace

Actual pairwise overlaps of compact finite-etale chart models are compact.

Source context 11 commands

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

noncomputable section
universe u
open CategoryTheory Limits
namespace AlgebraicGeometry.Scheme.Cover
variable {S : Scheme.{u}} (𝒰 : S.OpenCover)
variable (A : 𝒰.I₀ → Over S) (V : 𝒰.I₀ × 𝒰.I₀ → Over S)
variable (d : ∀ i j : 𝒰.I₀, V (i, j) ⟶ A i)
variable (y : ∀ i : 𝒰.I₀, (A i).left ⟶ 𝒰.X i)
variable (ℓ : ∀ i j : 𝒰.I₀, (V (i, j)).left ⟶ 𝒰.X j)
variable (hV : ∀ i j : 𝒰.I₀, IsPullback (d i j).left (ℓ i j) (y i ≫ 𝒰.f i) (𝒰.f j))
include hV in
theorem relativeOverlap_compactSpace [QuasiSeparatedSpace S]
    [∀ i : 𝒰.I₀, CompactSpace (𝒰.X i)] [∀ i : 𝒰.I₀, IsFiniteEtale (y i)]
    (i j : 𝒰.I₀) : CompactSpace (V (i, j)).left
AlgebraicGeometry.Scheme.Cover.relativeOverlap_locallyOfFiniteType

The actual overlap structural morphism is locally of finite type.

Source context 11 commands

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

noncomputable section
universe u
open CategoryTheory Limits
namespace AlgebraicGeometry.Scheme.Cover
variable {S : Scheme.{u}} (𝒰 : S.OpenCover)
variable (A : 𝒰.I₀ → Over S) (V : 𝒰.I₀ × 𝒰.I₀ → Over S)
variable (d : ∀ i j : 𝒰.I₀, V (i, j) ⟶ A i)
variable (y : ∀ i : 𝒰.I₀, (A i).left ⟶ 𝒰.X i)
variable (ℓ : ∀ i j : 𝒰.I₀, (V (i, j)).left ⟶ 𝒰.X j)
variable (hV : ∀ i j : 𝒰.I₀, IsPullback (d i j).left (ℓ i j) (y i ≫ 𝒰.f i) (𝒰.f j))
include hV in
theorem relativeOverlap_locallyOfFiniteType
    [∀ i : 𝒰.I₀, IsFiniteEtale (y i)]
    (hy : ∀ i : 𝒰.I₀, y i ≫ 𝒰.f i = (A i).hom) (i j : 𝒰.I₀) :
    LocallyOfFiniteType (V (i, j)).hom
AlgebraicGeometry.Scheme.Cover.relativeTriple_compactSpace

Actual triple intersections are compact; only quasi-separatedness of the ambient base is needed in addition to the compact local chart models.

Source context 11 commands

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

noncomputable section
universe u
open CategoryTheory Limits
namespace AlgebraicGeometry.Scheme.Cover
variable {S : Scheme.{u}} (𝒰 : S.OpenCover)
variable (A : 𝒰.I₀ → Over S) (V : 𝒰.I₀ × 𝒰.I₀ → Over S)
variable (d : ∀ i j : 𝒰.I₀, V (i, j) ⟶ A i)
variable (y : ∀ i : 𝒰.I₀, (A i).left ⟶ 𝒰.X i)
variable (ℓ : ∀ i j : 𝒰.I₀, (V (i, j)).left ⟶ 𝒰.X j)
variable (hV : ∀ i j : 𝒰.I₀, IsPullback (d i j).left (ℓ i j) (y i ≫ 𝒰.f i) (𝒰.f j))
include hV in
theorem relativeTriple_compactSpace [QuasiSeparatedSpace S]
    [∀ i : 𝒰.I₀, CompactSpace (𝒰.X i)] [∀ i : 𝒰.I₀, IsFiniteEtale (y i)]
    (i j k : 𝒰.I₀) : CompactSpace (relativeTriple 𝒰 A V d i j k).left
AlgebraicGeometry.Scheme.Cover.relativeTriple_locallyOfFiniteType

The actual triple-overlap structural morphism is locally of finite type.

Source context 11 commands

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

noncomputable section
universe u
open CategoryTheory Limits
namespace AlgebraicGeometry.Scheme.Cover
variable {S : Scheme.{u}} (𝒰 : S.OpenCover)
variable (A : 𝒰.I₀ → Over S) (V : 𝒰.I₀ × 𝒰.I₀ → Over S)
variable (d : ∀ i j : 𝒰.I₀, V (i, j) ⟶ A i)
variable (y : ∀ i : 𝒰.I₀, (A i).left ⟶ 𝒰.X i)
variable (ℓ : ∀ i j : 𝒰.I₀, (V (i, j)).left ⟶ 𝒰.X j)
variable (hV : ∀ i j : 𝒰.I₀, IsPullback (d i j).left (ℓ i j) (y i ≫ 𝒰.f i) (𝒰.f j))
include hV in
theorem relativeTriple_locallyOfFiniteType
    [∀ i : 𝒰.I₀, IsFiniteEtale (y i)]
    (hy : ∀ i : 𝒰.I₀, y i ≫ 𝒰.f i = (A i).hom) (i j k : 𝒰.I₀) :
    LocallyOfFiniteType (relativeTriple 𝒰 A V d i j k).hom