Module

CanonicalMaps.lean

Nyll.ProCGroups.CompletedGroupAlgebra.OpenFiniteQuotientTopology.CanonicalMaps
37 declarations indexed from sourceView source ↗

Completed Group Algebra / Open Finite Quotient Topology / Canonical Maps

This module constructs the canonical dense maps from the abstract group algebra to the \(C\)-indexed and all-finite named completions, together with their bundled ring, algebra, and linear forms and finite-stage characterizations.

Declarations

CompletedGroupAlgebra.completedGroupAlgebraStageMapInClass

The quotient map from the abstract group algebra \(R[G]\) to one \(C\)-indexed finite 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]
def completedGroupAlgebraStageMapInClass
    (C : ProCGroups.FiniteGroupClass.{v}) (R : Type u) (G : Type v) [CommRing R]
    [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
    (U : CompletedGroupAlgebraIndexInClass G C) :
    MonoidAlgebra R G →+* CompletedGroupAlgebraStageInClass C R G U
CompletedGroupAlgebra.completedGroupAlgebraStageMapInClass_of

At a \(C\)-indexed stage \(U\), the quotient map sends the group-like element of \(g\) to the singleton at the image of \(g\) in \(G/U\), with coefficient \(1\).

Source context 12 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]
omit [TopologicalSpace R] [IsTopologicalRing R] in
theorem completedGroupAlgebraStageMapInClass_of
    (C : ProCGroups.FiniteGroupClass.{v}) (U : CompletedGroupAlgebraIndexInClass G C)
    (g : G) :
    completedGroupAlgebraStageMapInClass C R G U (MonoidAlgebra.of R G g) =
      MonoidAlgebra.single (openNormalSubgroupInClassProj (C := C) (G := G) U g) 1
CompletedGroupAlgebra.completedGroupAlgebraStageMapInClass_single

At a \(C\)-indexed stage \(U\), the quotient map sends the singleton at \(g\) with coefficient \(r\) to the singleton at the image of \(g\) in \(G/U\), with coefficient \(r\).

Source context 12 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]
omit [TopologicalSpace R] [IsTopologicalRing R] in
theorem completedGroupAlgebraStageMapInClass_single
    (C : ProCGroups.FiniteGroupClass.{v}) (U : CompletedGroupAlgebraIndexInClass G C)
    (g : G) (r : R) :
    completedGroupAlgebraStageMapInClass C R G U (MonoidAlgebra.single g r) =
      MonoidAlgebra.single (openNormalSubgroupInClassProj (C := C) (G := G) U g) r
CompletedGroupAlgebra.completedGroupAlgebraStageMapInClass_smul

The \(C\)-indexed quotient-stage map preserves scalar multiplication by elements of \(R\).

Source context 12 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]
omit [TopologicalSpace R] [IsTopologicalRing R] in
theorem completedGroupAlgebraStageMapInClass_smul
    (C : ProCGroups.FiniteGroupClass.{v}) (U : CompletedGroupAlgebraIndexInClass G C)
    (r : R) (x : MonoidAlgebra R G) :
    completedGroupAlgebraStageMapInClass C R G U (r • x) =
      r • completedGroupAlgebraStageMapInClass C R G U x
CompletedGroupAlgebra.completedGroupAlgebraStageMapInClass_algebraMap

The \(C\)-indexed quotient-stage map commutes with the canonical embeddings of scalars from \(R\).

Source context 12 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]
omit [TopologicalSpace R] [IsTopologicalRing R] in
theorem completedGroupAlgebraStageMapInClass_algebraMap
    (C : ProCGroups.FiniteGroupClass.{v}) (U : CompletedGroupAlgebraIndexInClass G C)
    (r : R) :
    completedGroupAlgebraStageMapInClass C R G U (algebraMap R (MonoidAlgebra R G) r) =
      algebraMap R (CompletedGroupAlgebraStageInClass C R G U) r
CompletedGroupAlgebra.completedGroupAlgebraStageMapInClass_surjective

The quotient map \(R[G]\to R[G/U]\) is surjective for every \(C\)-indexed stage \(U\).

Source context 12 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]
omit [TopologicalSpace R] [IsTopologicalRing R] in
theorem completedGroupAlgebraStageMapInClass_surjective
    (C : ProCGroups.FiniteGroupClass.{v}) (U : CompletedGroupAlgebraIndexInClass G C) :
    Function.Surjective (completedGroupAlgebraStageMapInClass C R G U)
CompletedGroupAlgebra.completedGroupAlgebraStageMapInClass_compatible

The class-restricted completed group-algebra stage map is compatible with transition maps and coordinate projections for the completed group algebra.

Source context 12 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]
omit [TopologicalSpace R] [IsTopologicalRing R] in
theorem completedGroupAlgebraStageMapInClass_compatible
    (C : ProCGroups.FiniteGroupClass.{v})
    {U V : CompletedGroupAlgebraIndexInClass G C} (hUV : U ≤ V) :
    (completedGroupAlgebraTransitionInClass C R G hUV).comp
        (completedGroupAlgebraStageMapInClass C R G V) =
      completedGroupAlgebraStageMapInClass C R G U
CompletedGroupAlgebra.completedGroupAlgebraStageMapInClass_compatibleMaps

The \(C\)-indexed finite-stage quotient maps form a compatible family.

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 completedGroupAlgebraStageMapInClass_compatibleMaps
    (C : ProCGroups.FiniteGroupClass.{v}) :
    (completedGroupAlgebraSystemInClass C R G).CompatibleMaps
      (fun U => completedGroupAlgebraStageMapInClass C R G U) := by
  intro U V hUV
  funext x
  exact congrFun
    (congrArg DFunLike.coe
      (completedGroupAlgebraStageMapInClass_compatible (R := R) (G := G) C hUV))
    x
CompletedGroupAlgebra.toCompletedGroupAlgebraInClass

The canonical map \(R[G] \to \widehat{R[G]}_C\), obtained from all \(C\)-indexed quotient maps.

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 toCompletedGroupAlgebraInClass
    (C : ProCGroups.FiniteGroupClass.{v})
    (R : Type u) (G : Type v) [CommRing R] [TopologicalSpace R] [IsTopologicalRing R]
    [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
    (x : MonoidAlgebra R G) : CompletedGroupAlgebraInClass C R G
CompletedGroupAlgebra.completedGroupAlgebraProjectionInClass_toCompletedGroupAlgebraInClass

The \(U\)-coordinate of the canonical dense element in the \(C\)-indexed completion is the \(C\)-indexed stage map at \(U\).

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 completedGroupAlgebraProjectionInClass_toCompletedGroupAlgebraInClass
    (C : ProCGroups.FiniteGroupClass.{v})
    (U : CompletedGroupAlgebraIndexInClass G C) (x : MonoidAlgebra R G) :
    completedGroupAlgebraProjectionInClass C R G U
        (toCompletedGroupAlgebraInClass C R G x) =
      completedGroupAlgebraStageMapInClass C R G U x
CompletedGroupAlgebra.toCompletedGroupAlgebraInClass_smul

The canonical map from \(R[G]\) into the \(C\)-indexed completed group algebra preserves scalar multiplication by \(R\).

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 toCompletedGroupAlgebraInClass_smul
    (C : ProCGroups.FiniteGroupClass.{v})
    (r : R) (x : MonoidAlgebra R G) :
    toCompletedGroupAlgebraInClass C R G (r • x) =
      r • toCompletedGroupAlgebraInClass C R G x
CompletedGroupAlgebra.toCompletedGroupAlgebraInClassRingHom

The canonical map \(R[G] \to \widehat{R[G]}_C\) is bundled as a ring homomorphism.

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 toCompletedGroupAlgebraInClassRingHom
    (C : ProCGroups.FiniteGroupClass.{v})
    (R : Type u) (G : Type v) [CommRing R] [TopologicalSpace R] [IsTopologicalRing R]
    [Group G] [TopologicalSpace G] [IsTopologicalGroup G] :
    MonoidAlgebra R G →+* CompletedGroupAlgebraInClass C R G where
  toFun := toCompletedGroupAlgebraInClass C R G
  map_zero' := by
    apply completedGroupAlgebraInClass_ext (R := R) (G := G) C
    intro U
    exact map_zero (completedGroupAlgebraStageMapInClass C R G U)
  map_one' := by
    apply completedGroupAlgebraInClass_ext (R := R) (G := G) C
    intro U
    exact map_one (completedGroupAlgebraStageMapInClass C R G U)
  map_add' x y := by
    apply completedGroupAlgebraInClass_ext (R := R) (G := G) C
    intro U
    exact map_add (completedGroupAlgebraStageMapInClass C R G U) x y
  map_mul' x y := by
    apply completedGroupAlgebraInClass_ext (R := R) (G := G) C
    intro U
    exact map_mul (completedGroupAlgebraStageMapInClass C R G U) x y
CompletedGroupAlgebra.toCompletedGroupAlgebraInClassRingHom_apply

The bundled ring homomorphism has the same underlying function as the coordinatewise construction.

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 toCompletedGroupAlgebraInClassRingHom_apply
    (C : ProCGroups.FiniteGroupClass.{v})
    (x : MonoidAlgebra R G) :
    toCompletedGroupAlgebraInClassRingHom C R G x =
      toCompletedGroupAlgebraInClass C R G x
CompletedGroupAlgebra.toCompletedGroupAlgebraInClassAlgHom

The canonical map \(R[G] \to \widehat{R[G]}_C\), as an algebra homomorphism.

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 toCompletedGroupAlgebraInClassAlgHom
    (C : ProCGroups.FiniteGroupClass.{v})
    (R : Type u) (G : Type v) [CommRing R] [TopologicalSpace R] [IsTopologicalRing R]
    [Group G] [TopologicalSpace G] [IsTopologicalGroup G] :
    MonoidAlgebra R G →ₐ[R] CompletedGroupAlgebraInClass C R G where
  toRingHom := toCompletedGroupAlgebraInClassRingHom C R G
  commutes' := by
    intro r
    apply completedGroupAlgebraInClass_ext (R := R) (G := G) C
    intro U
    change completedGroupAlgebraStageMapInClass C R G U
        (algebraMap R (MonoidAlgebra R G) r) =
      algebraMap R (CompletedGroupAlgebraStageInClass C R G U) r
    exact completedGroupAlgebraStageMapInClass_algebraMap (R := R) (G := G) C U r
CompletedGroupAlgebra.toCompletedGroupAlgebraInClassAlgHom_apply

Evaluating the canonical \(C\)-indexed algebra homomorphism gives the coordinatewise dense map toCompletedGroupAlgebraInClass.

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 toCompletedGroupAlgebraInClassAlgHom_apply
    (C : ProCGroups.FiniteGroupClass.{v})
    (x : MonoidAlgebra R G) :
    toCompletedGroupAlgebraInClassAlgHom C R G x =
      toCompletedGroupAlgebraInClass C R G x
CompletedGroupAlgebra.toCompletedGroupAlgebraInClassLinearMap

The canonical map \(R[G] \to \widehat{R[G]}_C\), as a linear map.

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 toCompletedGroupAlgebraInClassLinearMap
    (C : ProCGroups.FiniteGroupClass.{v})
    (R : Type u) (G : Type v) [CommRing R] [TopologicalSpace R] [IsTopologicalRing R]
    [Group G] [TopologicalSpace G] [IsTopologicalGroup G] :
    MonoidAlgebra R G →ₗ[R] CompletedGroupAlgebraInClass C R G where
  toFun := toCompletedGroupAlgebraInClass C R G
  map_add' := by
    intro x y
    exact map_add (toCompletedGroupAlgebraInClassRingHom C R G) x y
  map_smul' := toCompletedGroupAlgebraInClass_smul (R := R) (G := G) C
CompletedGroupAlgebra.toCompletedGroupAlgebraInClassLinearMap_apply

The bundled linear map has the same underlying function as the coordinatewise construction.

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 toCompletedGroupAlgebraInClassLinearMap_apply
    (C : ProCGroups.FiniteGroupClass.{v})
    (x : MonoidAlgebra R G) :
    toCompletedGroupAlgebraInClassLinearMap C R G x =
      toCompletedGroupAlgebraInClass C R G x
CompletedGroupAlgebra.completedGAProjectionInClass_comp_toCompletedGAInClass

Composing the \(U\)-coordinate projection from the \(C\)-indexed completion with its canonical dense ring homomorphism gives the \(C\)-indexed stage map at \(U\).

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 completedGAProjectionInClass_comp_toCompletedGAInClass
    (C : ProCGroups.FiniteGroupClass.{v})
    (U : CompletedGroupAlgebraIndexInClass G C) :
    (completedGroupAlgebraProjectionInClass C R G U).comp
        (toCompletedGroupAlgebraInClassRingHom C R G) =
      completedGroupAlgebraStageMapInClass C R G U
CompletedGroupAlgebra.denseRange_toCompletedGroupAlgebraInClass

The abstract group algebra is dense in the \(C\)-indexed completed group algebra when \(G\) is pro-\(C\) and \(C\) is a formation.

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 denseRange_toCompletedGroupAlgebraInClass
    (C : ProCGroups.FiniteGroupClass.{v})
    (hForm : ProCGroups.FiniteGroupClass.Formation C) (hG : HasOpenNormalBasisInClass C G) :
    DenseRange (toCompletedGroupAlgebraInClass C R G)
CompletedGroupAlgebra.completedGroupAlgebraTransition_comp_projection

Projecting to a finer stage \(V\) and then applying the transition to \(U\) agrees with projecting directly to \(U\).

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 completedGroupAlgebraTransition_comp_projection
    {U V : CompletedGroupAlgebraIndex G} (hUV : U ≤ V) :
    (completedGroupAlgebraTransition R G hUV).comp
        (completedGroupAlgebraProjection R G V) =
      completedGroupAlgebraProjection R G U
CompletedGroupAlgebra.completedGroupAlgebraStageMap

The quotient map from the abstract group algebra \(R[G]\) to one finite stage \(R[G/U]\).

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 completedGroupAlgebraStageMap (R : Type u) (G : Type v) [CommRing R] [Group G]
    [TopologicalSpace G] [IsTopologicalGroup G] (U : CompletedGroupAlgebraIndex G) :
    MonoidAlgebra R G →+* CompletedGroupAlgebraStage R G U
CompletedGroupAlgebra.completedGroupAlgebraStageMap_of

At an all-finite stage \(U\), the quotient map sends the group-like element of \(g\) to the singleton at the image of \(g\) in \(G/U\), with coefficient \(1\).

Source context 12 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]
omit [TopologicalSpace R] [IsTopologicalRing R] in
theorem completedGroupAlgebraStageMap_of
    (U : CompletedGroupAlgebraIndex G) (g : G) :
    completedGroupAlgebraStageMap R G U (MonoidAlgebra.of R G g) =
      MonoidAlgebra.single (openNormalSubgroupInClassProj
        (C := ProCGroups.FiniteGroupClass.allFinite) (G := G) U g) 1
CompletedGroupAlgebra.completedGroupAlgebraStageMap_single

At an all-finite stage \(U\), the quotient map sends the singleton at \(g\) with coefficient \(r\) to the singleton at the image of \(g\) in \(G/U\), with coefficient \(r\).

Source context 12 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]
omit [TopologicalSpace R] [IsTopologicalRing R] in
theorem completedGroupAlgebraStageMap_single
    (U : CompletedGroupAlgebraIndex G) (g : G) (r : R) :
    completedGroupAlgebraStageMap R G U (MonoidAlgebra.single g r) =
      MonoidAlgebra.single (openNormalSubgroupInClassProj
        (C := ProCGroups.FiniteGroupClass.allFinite) (G := G) U g) r
CompletedGroupAlgebra.completedGroupAlgebraStageMap_smul

The all-finite quotient-stage map preserves scalar multiplication by elements of \(R\).

Source context 12 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]
omit [TopologicalSpace R] [IsTopologicalRing R] in
theorem completedGroupAlgebraStageMap_smul
    (U : CompletedGroupAlgebraIndex G) (r : R) (x : MonoidAlgebra R G) :
    completedGroupAlgebraStageMap R G U (r • x) =
      r • completedGroupAlgebraStageMap R G U x
CompletedGroupAlgebra.completedGroupAlgebraStageMap_algebraMap

The all-finite quotient-stage map commutes with the canonical embeddings of scalars from \(R\).

Source context 12 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]
omit [TopologicalSpace R] [IsTopologicalRing R] in
theorem completedGroupAlgebraStageMap_algebraMap
    (U : CompletedGroupAlgebraIndex G) (r : R) :
    completedGroupAlgebraStageMap R G U (algebraMap R (MonoidAlgebra R G) r) =
      algebraMap R (CompletedGroupAlgebraStage R G U) r
CompletedGroupAlgebra.completedGroupAlgebraStageMap_surjective

The quotient map \(R[G]\to R[G/U]\) is surjective for every all-finite stage \(U\).

Source context 12 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]
omit [TopologicalSpace R] [IsTopologicalRing R] in
theorem completedGroupAlgebraStageMap_surjective (U : CompletedGroupAlgebraIndex G) :
    Function.Surjective (completedGroupAlgebraStageMap R G U)
CompletedGroupAlgebra.completedGroupAlgebraStageMap_compatible

The completed group-algebra stage map is compatible with transition maps and coordinate projections for the completed group algebra.

Source context 12 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]
omit [TopologicalSpace R] [IsTopologicalRing R] in
theorem completedGroupAlgebraStageMap_compatible
    {U V : CompletedGroupAlgebraIndex G} (hUV : U ≤ V) :
    (completedGroupAlgebraTransition R G hUV).comp (completedGroupAlgebraStageMap R G V) =
      completedGroupAlgebraStageMap R G U
CompletedGroupAlgebra.completedGroupAlgebraStageMap_compatibleMaps

The finite-stage quotient maps form a compatible family into the completed group algebra system.

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 completedGroupAlgebraStageMap_compatibleMaps :
    (completedGroupAlgebraSystem R G).CompatibleMaps
      (fun U => completedGroupAlgebraStageMap R G U) := by
  intro U V hUV
  funext x
  exact congrFun
    (congrArg DFunLike.coe
      (completedGroupAlgebraStageMap_compatible (R := R) (G := G) (U := U) (V := V) hUV))
    x
CompletedGroupAlgebra.toCompletedGroupAlgebra

The canonical map \(R[G] \to \widehat{R[G]}\), obtained from all quotient maps \(R[G]\to R[G/U]\).

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 toCompletedGroupAlgebra (R : Type u) (G : Type v) [CommRing R] [TopologicalSpace R]
    [IsTopologicalRing R] [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
    (x : MonoidAlgebra R G) : CompletedGroupAlgebraCarrier R G
CompletedGroupAlgebra.completedGroupAlgebraProjection_toCompletedGroupAlgebra

The \(U\)-coordinate of the canonical dense element in the all-finite completion is the all-finite stage map at \(U\).

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_toCompletedGroupAlgebra
    (U : CompletedGroupAlgebraIndex G) (x : MonoidAlgebra R G) :
    completedGroupAlgebraProjection R G U (toCompletedGroupAlgebra R G x) =
      completedGroupAlgebraStageMap R G U x
CompletedGroupAlgebra.toCompletedGroupAlgebra_smul

The canonical map from \(R[G]\) into the all-finite completed group algebra preserves scalar multiplication by \(R\).

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 toCompletedGroupAlgebra_smul (r : R) (x : MonoidAlgebra R G) :
    toCompletedGroupAlgebra R G (r • x) =
      r • toCompletedGroupAlgebra R G x
CompletedGroupAlgebra.toCompletedGroupAlgebraRingHom

The canonical map \(R[G] \to \widehat{R[G]}\) is bundled as a ring homomorphism.

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 toCompletedGroupAlgebraRingHom (R : Type u) (G : Type v) [CommRing R]
    [TopologicalSpace R] [IsTopologicalRing R] [Group G] [TopologicalSpace G]
    [IsTopologicalGroup G] :
    MonoidAlgebra R G →+* CompletedGroupAlgebraCarrier R G where
  toFun := toCompletedGroupAlgebra R G
  map_zero' := by
    apply completedGroupAlgebra_ext (R := R) (G := G)
    intro U
    exact map_zero (completedGroupAlgebraStageMap R G U)
  map_one' := by
    apply completedGroupAlgebra_ext (R := R) (G := G)
    intro U
    exact map_one (completedGroupAlgebraStageMap R G U)
  map_add' x y := by
    apply completedGroupAlgebra_ext (R := R) (G := G)
    intro U
    exact map_add (completedGroupAlgebraStageMap R G U) x y
  map_mul' x y := by
    apply completedGroupAlgebra_ext (R := R) (G := G)
    intro U
    exact map_mul (completedGroupAlgebraStageMap R G U) x y
CompletedGroupAlgebra.completedGroupAlgebraToInClass_comp_toCompletedGroupAlgebra

Restricting the all-finite completion to its \(C\)-indexed coordinates after applying the all-finite dense map agrees with the canonical \(C\)-indexed dense map.

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 completedGroupAlgebraToInClass_comp_toCompletedGroupAlgebra
    (C : ProCGroups.FiniteGroupClass.{v}) :
    (completedGroupAlgebraToInClassRingHom (R := R) (G := G) C ).comp
        (toCompletedGroupAlgebraRingHom R G) =
      toCompletedGroupAlgebraInClassRingHom C R G
CompletedGroupAlgebra.completedGroupAlgebraFromInClassRingHom_comp_toCompletedGroupAlgebraInClass

Under the formation and pro-\(C\) hypotheses, transporting the \(C\)-indexed dense map back to the all-finite completion recovers the all-finite dense map.

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 completedGroupAlgebraFromInClassRingHom_comp_toCompletedGroupAlgebraInClass
    (C : ProCGroups.FiniteGroupClass.{v})
    (hForm : ProCGroups.FiniteGroupClass.Formation C) (hG : HasOpenNormalBasisInClass C G) :
    (completedGroupAlgebraFromInClassRingHom (R := R) (G := G) C hForm hG).comp
        (toCompletedGroupAlgebraInClassRingHom C R G) =
      toCompletedGroupAlgebraRingHom R G
CompletedGroupAlgebra.toCompletedGroupAlgebraAlgHom

The canonical map \(R[G] \to \widehat{R[G]}\) as an \(R\)-algebra homomorphism.

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 toCompletedGroupAlgebraAlgHom (R : Type u) (G : Type v) [CommRing R]
    [TopologicalSpace R] [IsTopologicalRing R] [Group G] [TopologicalSpace G]
    [IsTopologicalGroup G] :
    MonoidAlgebra R G →ₐ[R] CompletedGroupAlgebraCarrier R G where
  toRingHom := toCompletedGroupAlgebraRingHom R G
  commutes' := by
    intro r
    apply completedGroupAlgebra_ext (R := R) (G := G)
    intro U
    change completedGroupAlgebraStageMap R G U (algebraMap R (MonoidAlgebra R G) r) =
      algebraMap R (CompletedGroupAlgebraStage R G U) r
    exact completedGroupAlgebraStageMap_algebraMap (R := R) (G := G) U r
CompletedGroupAlgebra.toCompletedGroupAlgebraLinearMap

The canonical map \(R[G] \to \widehat{R[G]}\) as an \(R\)-linear map.

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 toCompletedGroupAlgebraLinearMap (R : Type u) (G : Type v) [CommRing R]
    [TopologicalSpace R] [IsTopologicalRing R] [Group G] [TopologicalSpace G]
    [IsTopologicalGroup G] :
    MonoidAlgebra R G →ₗ[R] CompletedGroupAlgebraCarrier R G where
  toFun := toCompletedGroupAlgebra R G
  map_add' := by
    intro x y
    exact map_add (toCompletedGroupAlgebraRingHom R G) x y
  map_smul' := toCompletedGroupAlgebra_smul (R := R) (G := G)
CompletedGroupAlgebra.completedGroupAlgebraProjection_comp_toCompletedGroupAlgebra

Composing the \(U\)-coordinate projection from the all-finite completion with its canonical dense ring homomorphism gives the all-finite stage map at \(U\).

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_comp_toCompletedGroupAlgebra
    (U : CompletedGroupAlgebraIndex G) :
    (completedGroupAlgebraProjection R G U).comp
        (toCompletedGroupAlgebraRingHom R G) =
      completedGroupAlgebraStageMap R G U