Module

StageMap.lean

Nyll.ProCGroups.CompletedGroupAlgebra.AllFiniteFunctoriality.StageMap
7 declarations indexed from sourceView source ↗

Completed Group Algebra / All Finite Functoriality / Stage Map

This module lifts the quotient homomorphism from Comap to finite group algebras and proves its continuity, transition compatibility, and compatibility with the canonical dense stage maps.

Declarations

CompletedGroupAlgebra.completedGroupAlgebraFunctorialStageMap

The finite-stage map \(R[G/\varphi^{-1}(V)]\to R[H/V]\) is induced by the continuous homomorphism \(\varphi : G \to H\).

Source context 9 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
universe u v w
variable (R : Type u) [CommRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
def completedGroupAlgebraFunctorialStageMap
    (R : Type u) [CommRing R]
    (φ : G →* H) (hφ : Continuous φ) (V : CompletedGroupAlgebraIndex H) :
    CompletedGroupAlgebraStage R G (completedGroupAlgebraComapIndex (G := G) φ hφ V) →+*
      CompletedGroupAlgebraStage R H V
CompletedGroupAlgebra.completedGroupAlgebraFunctorialStageMap_surjective_of_surjective

A surjective group homomorphism induces a surjective finite-stage algebra map.

Source context 9 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
universe u v w
variable (R : Type u) [CommRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
theorem completedGroupAlgebraFunctorialStageMap_surjective_of_surjective
    (φ : G →* H) (hφ : Continuous φ)
    (hφsurj : Function.Surjective φ) (V : CompletedGroupAlgebraIndex H) :
    Function.Surjective
      (completedGroupAlgebraFunctorialStageMap
        (G := G) (H := H) (R := R) φ hφ V)
CompletedGroupAlgebra.completedGroupAlgebraFunctorialStageMap_single

The finite-stage functorial map induced by \(\varphi : G \to H\) carries a singleton basis function on \(G/\varphi^{-1}(V)\) to the singleton basis function on \(H/V\) supported at the induced image, with unchanged coefficient.

Source context 9 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
universe u v w
variable (R : Type u) [CommRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
theorem completedGroupAlgebraFunctorialStageMap_single
    (φ : G →* H) (hφ : Continuous φ)
    (V : CompletedGroupAlgebraIndex H)
    (q : CompletedGroupAlgebraQuotient G
      (completedGroupAlgebraComapIndex (G := G) φ hφ V)) (r : R) :
    completedGroupAlgebraFunctorialStageMap (G := G) (H := H) (R := R) φ hφ V
        (MonoidAlgebra.single q r) =
      MonoidAlgebra.single (completedGroupAlgebraComapQuotientMap (G := G) φ hφ V q) r
CompletedGroupAlgebra.completedGroupAlgebraFunctorialStageMap_algebraMap

The finite-stage functorial map preserves scalar algebra-map elements.

Source context 9 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
universe u v w
variable (R : Type u) [CommRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
theorem completedGroupAlgebraFunctorialStageMap_algebraMap
    (φ : G →* H) (hφ : Continuous φ)
    (V : CompletedGroupAlgebraIndex H) (r : R) :
    completedGroupAlgebraFunctorialStageMap (G := G) (H := H) (R := R) φ hφ V
        (algebraMap R
          (CompletedGroupAlgebraStage R G
            (completedGroupAlgebraComapIndex (G := G) φ hφ V)) r) =
      algebraMap R (CompletedGroupAlgebraStage R H V) r
CompletedGroupAlgebra.continuous_completedGroupAlgebraFunctorialStageMap

The finite-stage functorial map is continuous for the finite-stage topologies.

Source context 9 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
universe u v w
variable (R : Type u) [CommRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
theorem continuous_completedGroupAlgebraFunctorialStageMap
    [TopologicalSpace R] [IsTopologicalRing R]
    (φ : G →* H) (hφ : Continuous φ)
    (V : CompletedGroupAlgebraIndex H) :
    letI : TopologicalSpace
        (CompletedGroupAlgebraStage R G (completedGroupAlgebraComapIndex (G := G) φ hφ V)) :=
      (completedGroupAlgebraSystem R G).topologicalSpace
        (completedGroupAlgebraComapIndex (G := G) φ hφ V)
    letI : TopologicalSpace (CompletedGroupAlgebraStage R H V) :=
      (completedGroupAlgebraSystem R H).topologicalSpace V
    Continuous (completedGroupAlgebraFunctorialStageMap (G := G) (H := H) (R := R)
      φ hφ V) := by
  let : TopologicalSpace
      (CompletedGroupAlgebraStage R G (completedGroupAlgebraComapIndex (G := G) φ hφ V)) :=
    (completedGroupAlgebraSystem R G).topologicalSpace
      (completedGroupAlgebraComapIndex (G := G) φ hφ V)
  let : TopologicalSpace (CompletedGroupAlgebraStage R H V) :=
    (completedGroupAlgebraSystem R H).topologicalSpace V
  exact finiteGroupAlgebra_mapDomainRingHom_continuous R
    (CompletedGroupAlgebraQuotient G (completedGroupAlgebraComapIndex (G := G) φ hφ V))
    (CompletedGroupAlgebraQuotient H V)
    (completedGroupAlgebraComapQuotientMap (G := G) φ hφ V)
CompletedGroupAlgebra.completedGroupAlgebraFunctorialStageMap_transition

Functorial finite-stage maps commute with the transition maps attached to refinements of finite quotients.

Source context 9 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
universe u v w
variable (R : Type u) [CommRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
theorem completedGroupAlgebraFunctorialStageMap_transition
    (φ : G →* H) (hφ : Continuous φ)
    {V W : CompletedGroupAlgebraIndex H} (hVW : V ≤ W) :
    (completedGroupAlgebraTransition R H hVW).comp
        (completedGroupAlgebraFunctorialStageMap (G := G) (H := H) (R := R) φ hφ W) =
      (completedGroupAlgebraFunctorialStageMap (G := G) (H := H) (R := R) φ hφ V).comp
        (completedGroupAlgebraTransition R G
          (completedGroupAlgebraComapIndex_mono (G := G) φ hφ hVW))
CompletedGroupAlgebra.completedGroupAlgebraFunctorialStageMap_comp_stageMap

The finite-stage functorial map agrees with the dense stage map after applying \(\varphi\).

Source context 9 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
universe u v w
variable (R : Type u) [CommRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
theorem completedGroupAlgebraFunctorialStageMap_comp_stageMap
    (φ : G →* H) (hφ : Continuous φ)
    (V : CompletedGroupAlgebraIndex H) :
    (completedGroupAlgebraFunctorialStageMap (G := G) (H := H) (R := R) φ hφ V).comp
        (completedGroupAlgebraStageMap R G
          (completedGroupAlgebraComapIndex (G := G) φ hφ V)) =
      (completedGroupAlgebraStageMap R H V).comp
        (MonoidAlgebra.mapDomainRingHom R φ)