Module

MultiplicativeInducedShapiro.lean

Nyll.GaloisCohomology.ProP.MultiplicativeInducedShapiro
3 declarations indexed from sourceView source ↗

Shapiro for the multiplicative induced local blocks

The concrete equivariant-function module used by the local idele block decomposition has exactly Mathlib's coinduced action after applying Additive. This file supplies the representation isomorphism and hence Shapiro in all degrees, for arbitrary ambient groups and subgroups.

Declarations

ClassFieldTower.Cohomology.multiplicativeInducedRepIsoCoind

The multiplicative equivariant-function induced module used by the local idele blocks is Mathlib's coinduced additive representation.

Source context 6 commands

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

open CategoryTheory
noncomputable section
namespace ClassFieldTower.Cohomology
open CyclicCohomology
variable {G : Type} [Group G] (H : Subgroup G)
variable (B : Type) [CommGroup B] [MulDistribMulAction H B]
def multiplicativeInducedRepIsoCoind :
    Rep.ofMulDistribMulAction G (InducedModule (B := B) H) ≅
      Rep.coind H.subtype (Rep.ofMulDistribMulAction H B)
ClassFieldTower.Cohomology.multiplicativeInducedCohomologyIso

Shapiro's lemma for the actual multiplicative induced module used in the finite-place idele decomposition, in every cohomological degree.

Source context 6 commands

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

open CategoryTheory
noncomputable section
namespace ClassFieldTower.Cohomology
open CyclicCohomology
variable {G : Type} [Group G] (H : Subgroup G)
variable (B : Type) [CommGroup B] [MulDistribMulAction H B]
def multiplicativeInducedCohomologyIso (i : ℕ) :
    groupCohomology (Rep.ofMulDistribMulAction G (InducedModule (B := B) H)) i ≅
      groupCohomology (Rep.ofMulDistribMulAction H B) i
ClassFieldTower.Cohomology.multiplicativeInducedCohomology_subsingleton

Vanishing passes from a subgroup representation to its concrete multiplicative induced module via the proved Shapiro isomorphism.

Source context 6 commands

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

open CategoryTheory
noncomputable section
namespace ClassFieldTower.Cohomology
open CyclicCohomology
variable {G : Type} [Group G] (H : Subgroup G)
variable (B : Type) [CommGroup B] [MulDistribMulAction H B]
theorem multiplicativeInducedCohomology_subsingleton (i : ℕ)
    [Subsingleton (groupCohomology (Rep.ofMulDistribMulAction H B) i)] :
    Subsingleton
      (groupCohomology (Rep.ofMulDistribMulAction G (InducedModule (B := B) H)) i)