Module

AwayToPrime.lean

Nyll.SchemeTheory.RingTheory.Localization.AwayToPrime
8 declarations indexed from sourceView source ↗

Native principal-localization maps to an actual prime localization

The source is the actual native principal localization. The target and its coefficient map are the existing native prime-localization owners. The single localization proof below closes the coefficient equation in an R/C-only scope. The base equation then uses only that proved equation and an ordinary coefficient-ring square, supplied in applications by the original inclusion.

Imports8
Imported by3

Declarations

SchemeTheory.principalLocalizationCommRingCat

The actual native principal localization, bundled with its native ring.

Source context 3 commands

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

noncomputable section
namespace SchemeTheory
universe u v w
def principalLocalizationCommRingCat (R : Type v) [CommRing R] (d : R) :
    CommRingCat.{v}
SchemeTheory.principalLocalizationCoefficientMap

The native coefficient map into the actual principal localization.

Source context 3 commands

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

noncomputable section
namespace SchemeTheory
universe u v w
def principalLocalizationCoefficientMap (R : Type v) [CommRing R] (d : R) :
    R →+* principalLocalizationCommRingCat R d
SchemeTheory.primeLocalizationCoefficientMap_comp_isUnit

A coefficient outside the actual prime becomes a unit under the computed native prime-localization map. This closes the target localization algebra before the principal-localization lift is used.

Source context 3 commands

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

noncomputable section
namespace SchemeTheory
universe u v w
theorem primeLocalizationCoefficientMap_comp_isUnit
    {R : Type v} {C : Type w} [CommRing R] [CommRing C]
    (f : R →+* C) (d : R) (Q : Ideal C) [Q.IsPrime] (h : f d ∉ Q) :
    IsUnit (((primeLocalizationCoefficientMap C Q).comp f) d)
SchemeTheory.principalLocalizationToPrimeMap

The native principal-localization lift of the actual coefficient map.

Source context 3 commands

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

noncomputable section
namespace SchemeTheory
universe u v w
def principalLocalizationToPrimeMap
    {R : Type v} {C : Type w} [CommRing R] [CommRing C]
    (f : R →+* C) (d : R) (Q : Ideal C) [Q.IsPrime] (h : f d ∉ Q) :
    principalLocalizationCommRingCat R d →+* primeLocalizationCommRingCat C Q
SchemeTheory.principalLocalizationToPrimeMap_comp_coefficient

The native coefficient equation, retained as an equality of computed RingHoms so later applications do not reopen the localization algebras.

Source context 3 commands

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

noncomputable section
namespace SchemeTheory
universe u v w
theorem principalLocalizationToPrimeMap_comp_coefficient
    {R : Type v} {C : Type w} [CommRing R] [CommRing C]
    (f : R →+* C) (d : R) (Q : Ideal C) [Q.IsPrime] (h : f d ∉ Q) :
    (principalLocalizationToPrimeMap f d Q h).comp
        (principalLocalizationCoefficientMap R d) =
      (primeLocalizationCoefficientMap C Q).comp f
SchemeTheory.principalLocalizationBaseMap

The original base-ring map into the actual principal localization.

Source context 3 commands

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

noncomputable section
namespace SchemeTheory
universe u v w
def principalLocalizationBaseMap (A : Type u) (R : Type v)
    [CommRing A] [CommRing R] [Algebra A R] (d : R) :
    A →+* principalLocalizationCommRingCat R d
SchemeTheory.principalLocalizationBaseMap_eq_algebraMap

The computed base map is the existing principal-localization algebra map. The scalar tower is the native one; no new action is installed.

Source context 3 commands

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

noncomputable section
namespace SchemeTheory
universe u v w
theorem principalLocalizationBaseMap_eq_algebraMap
    (A : Type u) (R : Type v) [CommRing A] [CommRing R] [Algebra A R] (d : R) :
    principalLocalizationBaseMap A R d =
      algebraMap A (localizationAwayCommAlgCat A R d)
SchemeTheory.principalLocalizationToPrimeMap_comp_base

An ordinary base square on the coefficient rings gives the closed base square for the actual principal-localization lift.

Source context 3 commands

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

noncomputable section
namespace SchemeTheory
universe u v w
theorem principalLocalizationToPrimeMap_comp_base
    (A : Type u) {R : Type v} {C : Type w}
    [CommRing A] [CommRing R] [CommRing C] [Algebra A R] [Algebra A C]
    (f : R →+* C) (d : R) (Q : Ideal C) [Q.IsPrime] (h : f d ∉ Q)
    (hbase : f.comp (algebraMap A R) = algebraMap A C) :
    (principalLocalizationToPrimeMap f d Q h).comp
        (principalLocalizationBaseMap A R d) =
      primeLocalizationBaseMap A C Q