Module

GroupLike.lean

Nyll.ProCGroups.CompletedGroupAlgebra.AllFiniteFunctoriality.GroupLike
8 declarations indexed from sourceView source ↗

Completed Group Algebra / All Finite Functoriality / Group-Like

This module records the action of the all-finite functorial map on canonical group-like elements.

Declarations

CompletedGroupAlgebra.completedGroupAlgebraOf

A group element maps to its image in the completed group algebra.

Source context 11 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
open ProCGroups.InverseSystems
open ProCGroups.Completion
universe u v w
variable (R : Type u) [CommRing R] [TopologicalSpace R] [IsTopologicalRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
def completedGroupAlgebraOf (R : Type u) (G : Type v) [CommRing R] [TopologicalSpace R]
    [IsTopologicalRing R] [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
    (g : G) : CompletedGroupAlgebraCarrier R G
CompletedGroupAlgebra.completedGroupAlgebraProjection_of

Projection of a completed group-like element to a finite quotient stage.

Source context 11 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
open ProCGroups.InverseSystems
open ProCGroups.Completion
universe u v w
variable (R : Type u) [CommRing R] [TopologicalSpace R] [IsTopologicalRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
theorem completedGroupAlgebraProjection_of
    (U : CompletedGroupAlgebraIndex G) (g : G) :
    completedGroupAlgebraProjection R G U (completedGroupAlgebraOf R G g) =
      MonoidAlgebra.single (openNormalSubgroupInClassProj
        (C := ProCGroups.FiniteGroupClass.allFinite) (G := G) U g) 1
CompletedGroupAlgebra.completedGroupAlgebraOf_one

The completed group-like element attached to \(1\) is the unit.

Source context 11 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
open ProCGroups.InverseSystems
open ProCGroups.Completion
universe u v w
variable (R : Type u) [CommRing R] [TopologicalSpace R] [IsTopologicalRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
theorem completedGroupAlgebraOf_one :
    completedGroupAlgebraOf R G 1 = (1 : CompletedGroupAlgebraCarrier R G)
CompletedGroupAlgebra.completedGroupAlgebraOf_mul

Completed group-like elements multiply according to the group law.

Source context 11 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
open ProCGroups.InverseSystems
open ProCGroups.Completion
universe u v w
variable (R : Type u) [CommRing R] [TopologicalSpace R] [IsTopologicalRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
theorem completedGroupAlgebraOf_mul (g h : G) :
    completedGroupAlgebraOf R G (g * h) =
      completedGroupAlgebraOf R G g * completedGroupAlgebraOf R G h
CompletedGroupAlgebra.continuous_completedGroupAlgebraStageMap_of

The finite-stage group-like map \(G\to R[G/U]\) is continuous.

Source context 11 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
open ProCGroups.InverseSystems
open ProCGroups.Completion
universe u v w
variable (R : Type u) [CommRing R] [TopologicalSpace R] [IsTopologicalRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
theorem continuous_completedGroupAlgebraStageMap_of
    (U : CompletedGroupAlgebraIndex G) :
    letI : TopologicalSpace (CompletedGroupAlgebraStage R G U) :=
      (completedGroupAlgebraSystem R G).topologicalSpace U
    Continuous fun g : G =>
      completedGroupAlgebraStageMap R G U (MonoidAlgebra.of R G g) := by
  let : TopologicalSpace (CompletedGroupAlgebraStage R G U) :=
    (completedGroupAlgebraSystem R G).topologicalSpace U
  let : DiscreteTopology (CompletedGroupAlgebraQuotient G U) :=
    QuotientGroup.discreteTopology
      (ProCGroups.openNormalSubgroup_isOpen
        (G := G) ((OrderDual.ofDual U).1 : OpenNormalSubgroup G))
  have hbasis :
      @Continuous (CompletedGroupAlgebraQuotient G U)
        (CompletedGroupAlgebraStage R G U) inferInstance
        ((completedGroupAlgebraSystem R G).topologicalSpace U)
        (fun q => MonoidAlgebra.single q (1 : R)) :=
    continuous_of_discreteTopology
  have hproj :
      Continuous fun g : G =>
        openNormalSubgroupInClassProj
          (C := ProCGroups.FiniteGroupClass.allFinite) (G := G) U g := by
    change Continuous
      (QuotientGroup.mk'
        (((OrderDual.ofDual U).1 : OpenNormalSubgroup G) : Subgroup G))
    exact continuous_quotient_mk'
  have hcont := hbasis.comp hproj
  change @Continuous G (CompletedGroupAlgebraStage R G U) (‹TopologicalSpace G›)
    ((completedGroupAlgebraSystem R G).topologicalSpace U)
    (fun g => MonoidAlgebra.single
      (openNormalSubgroupInClassProj
        (C := ProCGroups.FiniteGroupClass.allFinite) (G := G) U g) (1 : R)) at hcont
  convert hcont using 1
  funext g
  exact completedGroupAlgebraStageMap_of (R := R) (G := G) U g
CompletedGroupAlgebra.continuous_completedGroupAlgebraOf

The completed group-like map \(G \to \widehat{R[G]}\) is continuous.

Source context 11 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
open ProCGroups.InverseSystems
open ProCGroups.Completion
universe u v w
variable (R : Type u) [CommRing R] [TopologicalSpace R] [IsTopologicalRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
theorem continuous_completedGroupAlgebraOf :
    Continuous (completedGroupAlgebraOf R G)
CompletedGroupAlgebra.completedGroupAlgebraMap_of

The completed functorial map sends the group-like element attached to \(g\) to that of \(\varphi(g)\).

Source context 11 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
open ProCGroups.InverseSystems
open ProCGroups.Completion
universe u v w
variable (R : Type u) [CommRing R] [TopologicalSpace R] [IsTopologicalRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
theorem completedGroupAlgebraMap_of
    (φ : G →* H) (hφ : Continuous φ) (g : G) :
    completedGroupAlgebraMap (G := G) (H := H) R φ hφ (completedGroupAlgebraOf R G g) =
      completedGroupAlgebraOf R H (φ g)
CompletedGroupAlgebra.completedGroupAlgebraMapAlgHom_of

The algebra-hom completed functorial map sends group-like elements to their images.

Source context 11 commands

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

open scoped Topology
namespace CompletedGroupAlgebra
noncomputable section
open ProCGroups
open ProCGroups.ProC
open ProCGroups.InverseSystems
open ProCGroups.Completion
universe u v w
variable (R : Type u) [CommRing R] [TopologicalSpace R] [IsTopologicalRing R]
variable (G : Type v) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
variable {H : Type v} [Group H] [TopologicalSpace H] [IsTopologicalGroup H]
theorem completedGroupAlgebraMapAlgHom_of
    (φ : G →* H) (hφ : Continuous φ) (g : G) :
    completedGroupAlgebraMapAlgHom (G := G) (H := H) R φ hφ
        (completedGroupAlgebraOf R G g) =
      completedGroupAlgebraOf R H (φ g)