Module

Surjectivity.lean

Nyll.ProCGroups.CompletedGroupAlgebra.AllFiniteFunctoriality.Surjectivity
1 declaration indexed from sourceView source ↗

Surjectivity of completed group-algebra maps

A surjective continuous group homomorphism induces a surjective map of all-finite completed group algebras. The proof combines finite-stage surjectivity with the inverse-limit lifting argument.

Declarations

CompletedGroupAlgebra.completedGroupAlgebraMap_surjective_of_surjective

A surjective continuous homomorphism of profinite groups induces a surjective map on completed group algebras.

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] [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_surjective_of_surjective
    [CompactSpace R] [T2Space R] [TotallyDisconnectedSpace R]
    (φ : G →* H) (hφ : Continuous φ)
    (hφsurj : Function.Surjective φ) :
    Function.Surjective (completedGroupAlgebraMap (G := G) (H := H) R φ hφ)