Module

RawOverlapFiniteness.lean

Nyll.SchemeTheory.FiniteEtale.RawOverlapFiniteness
5 declarations indexed from sourceView source ↗

Actual finiteness hypotheses for raw overlap Hom descent

The local models are finite etale over affine charts. Their raw overlaps are open subschemes of affine models, and are compact because the original base is quasi-separated. Their ambient maps are locally finitely presented. No overlap is claimed finite over the whole ambient base.

Declarations

AlgebraicGeometry.Scheme.Cover.rawLocalModel_isAffine

Every actual local covering scheme is affine.

Source context 5 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)
    (M : ∀ i : 𝒰.I₀, Over (𝒰.X i))
    [∀ i : 𝒰.I₀, IsAffine (𝒰.X i)]
    [∀ i : 𝒰.I₀, IsFiniteEtale (M i).hom]
theorem rawLocalModel_isAffine (i : 𝒰.I₀) : IsAffine (M i).left
AlgebraicGeometry.Scheme.Cover.rawOverlap_compactSpace

Raw overlaps are compact over a quasi-separated ambient base.

Source context 5 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)
    (M : ∀ i : 𝒰.I₀, Over (𝒰.X i))
    [∀ i : 𝒰.I₀, IsAffine (𝒰.X i)]
    [∀ i : 𝒰.I₀, IsFiniteEtale (M i).hom]
theorem rawOverlap_compactSpace [QuasiSeparatedSpace S] (i j : 𝒰.I₀) :
    CompactSpace (gluingOverlapOver 𝒰 M (i, j)).left
AlgebraicGeometry.Scheme.Cover.rawOverlap_quasiCompact

The raw overlap ambient morphism is quasi-compact.

Source context 5 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)
    (M : ∀ i : 𝒰.I₀, Over (𝒰.X i))
    [∀ i : 𝒰.I₀, IsAffine (𝒰.X i)]
    [∀ i : 𝒰.I₀, IsFiniteEtale (M i).hom]
theorem rawOverlap_quasiCompact [QuasiSeparatedSpace S] (i j : 𝒰.I₀) :
    QuasiCompact (gluingOverlapOver 𝒰 M (i, j)).hom
AlgebraicGeometry.Scheme.Cover.rawOverlap_quasiSeparated

A raw overlap is an open subscheme of an affine local model, so its ambient structural map is quasi-separated.

Source context 5 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)
    (M : ∀ i : 𝒰.I₀, Over (𝒰.X i))
    [∀ i : 𝒰.I₀, IsAffine (𝒰.X i)]
    [∀ i : 𝒰.I₀, IsFiniteEtale (M i).hom]
theorem rawOverlap_quasiSeparated (i j : 𝒰.I₀) :
    QuasiSeparated (gluingOverlapOver 𝒰 M (i, j)).hom
AlgebraicGeometry.Scheme.Cover.rawOverlap_locallyOfFinitePresentation

The raw overlap ambient map is locally finitely presented: it is an open immersion followed by a finite-etale map and an open chart map.

Source context 6 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)
    (M : ∀ i : 𝒰.I₀, Over (𝒰.X i))
    [∀ i : 𝒰.I₀, IsAffine (𝒰.X i)]
    [∀ i : 𝒰.I₀, IsFiniteEtale (M i).hom]
omit [∀ i : 𝒰.I₀, IsAffine (𝒰.X i)] in
theorem rawOverlap_locallyOfFinitePresentation (i j : 𝒰.I₀) :
    LocallyOfFinitePresentation (gluingOverlapOver 𝒰 M (i, j)).hom