Module

AtMappedPrimeEquiv.lean

Nyll.SchemeTheory.RingTheory.Localization.AtMappedPrimeEquiv
3 declarations indexed from sourceView source ↗

Localizing a ring equivalence at a prime

An algebra equivalence carries the complement of a prime ideal onto the complement of its image. Hence it induces an algebra equivalence between the corresponding local rings. The explicit formula on elements from the base ring is retained for later transport of distinguished root parameters.

Declarations

EtaleFundamentalGroups.localizationAtMappedPrime_map_primeCompl

An algebra equivalence maps the complement of a prime onto the complement of the image prime.

Source context 6 commands

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

noncomputable section
namespace EtaleFundamentalGroups
universe uA uR uS
variable {A : Type uA} {R : Type uR} {S : Type uS}
variable [CommRing A] [CommRing R] [CommRing S]
variable [Algebra A R] [Algebra A S]
theorem localizationAtMappedPrime_map_primeCompl
    (e : R ≃ₐ[A] S) (P : Ideal R) [P.IsPrime] :
    Submonoid.map e P.primeCompl =
      (P.map e.toRingEquiv).primeCompl
EtaleFundamentalGroups.localizationAtMappedPrimeAlgEquiv

An algebra equivalence induces an algebra equivalence of the local rings at a prime and its image.

Source context 6 commands

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

noncomputable section
namespace EtaleFundamentalGroups
universe uA uR uS
variable {A : Type uA} {R : Type uR} {S : Type uS}
variable [CommRing A] [CommRing R] [CommRing S]
variable [Algebra A R] [Algebra A S]
def localizationAtMappedPrimeAlgEquiv
    (e : R ≃ₐ[A] S) (P : Ideal R) [P.IsPrime] :
    Localization.AtPrime P ≃ₐ[A]
      Localization.AtPrime (P.map e.toRingEquiv)
EtaleFundamentalGroups.localizationAtMappedPrimeAlgEquiv_algebraMap

On elements coming from the original ring, the localized equivalence is the original equivalence followed by the target localization map.

Source context 6 commands

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

noncomputable section
namespace EtaleFundamentalGroups
universe uA uR uS
variable {A : Type uA} {R : Type uR} {S : Type uS}
variable [CommRing A] [CommRing R] [CommRing S]
variable [Algebra A R] [Algebra A S]
theorem localizationAtMappedPrimeAlgEquiv_algebraMap
    (e : R ≃ₐ[A] S) (P : Ideal R) [P.IsPrime] (x : R) :
    localizationAtMappedPrimeAlgEquiv e P
        (algebraMap R (Localization.AtPrime P) x) =
      algebraMap S
        (Localization.AtPrime (P.map e.toRingEquiv)) (e x)