Module

Reduced.lean

Nyll.SchemeTheory.Divisors.Reduced
3 declarations indexed from sourceView source ↗

Reduced ideal sheaves and their closed subschemes

An ideal sheaf is radical exactly when its associated closed subscheme is reduced. This is checked on the canonical affine cover by the quotients Spec (Γ(X, U) / I(U)).

Declarations

AlgebraicGeometry.Scheme.IdealSheafData.IsReduced.subscheme

A radical ideal sheaf defines a reduced closed subscheme.

Source context 6 commands

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

noncomputable section
open CategoryTheory
namespace AlgebraicGeometry
universe u
namespace Scheme.IdealSheafData
variable {X : Scheme.{u}} (I : X.IdealSheafData)
theorem IsReduced.subscheme (hI : I.IsReduced) :
    AlgebraicGeometry.IsReduced I.subscheme
AlgebraicGeometry.Scheme.IdealSheafData.isReduced_of_subscheme

If the closed subscheme of an ideal sheaf is reduced, the ideal sheaf is radical.

Source context 6 commands

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

noncomputable section
open CategoryTheory
namespace AlgebraicGeometry
universe u
namespace Scheme.IdealSheafData
variable {X : Scheme.{u}} (I : X.IdealSheafData)
theorem isReduced_of_subscheme
    [AlgebraicGeometry.IsReduced I.subscheme] : I.IsReduced
AlgebraicGeometry.Scheme.IdealSheafData.isReduced_iff_subscheme_isReduced

Radicality of an ideal sheaf is equivalent to reducedness of its closed subscheme.

Source context 6 commands

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

noncomputable section
open CategoryTheory
namespace AlgebraicGeometry
universe u
namespace Scheme.IdealSheafData
variable {X : Scheme.{u}} (I : X.IdealSheafData)
theorem isReduced_iff_subscheme_isReduced :
    I.IsReduced ↔ AlgebraicGeometry.IsReduced I.subscheme