Module

ConnectedComponentQuotientCongr.lean

Nyll.ClassFieldTheory.AlgebraicNumberTheory.Idele.ClassGroup.ConnectedComponentQuotientCongr
3 declarations indexed from sourceView source ↗

Connected-component quotients under topological group equivalences

A topological group equivalence carries the connected component of one onto the connected component of one. It therefore induces an equivalence of the corresponding quotient topological groups.

Declarations

ClassFieldTheory.connectedComponentOfOne_map_equiv

A topological group equivalence maps the identity component exactly onto the identity component.

Source context 4 commands

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

noncomputable section
namespace ClassFieldTheory
universe u v
variable {G : Type u} {H : Type v}
  [Group G] [Group H]
  [TopologicalSpace G] [TopologicalSpace H]
  [IsTopologicalGroup G] [IsTopologicalGroup H]
theorem connectedComponentOfOne_map_equiv (e : G ≃ₜ* H) :
    (Subgroup.connectedComponentOfOne G).map e.toMulEquiv.toMonoidHom =
      Subgroup.connectedComponentOfOne H
ClassFieldTheory.connectedComponentQuotientCongr

An equivalence of topological groups descends to a topological group equivalence modulo the identity components.

Source context 4 commands

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

noncomputable section
namespace ClassFieldTheory
universe u v
variable {G : Type u} {H : Type v}
  [Group G] [Group H]
  [TopologicalSpace G] [TopologicalSpace H]
  [IsTopologicalGroup G] [IsTopologicalGroup H]
def connectedComponentQuotientCongr (e : G ≃ₜ* H) :
    (G ⧸ Subgroup.connectedComponentOfOne G) ≃ₜ*
      (H ⧸ Subgroup.connectedComponentOfOne H)
ClassFieldTheory.connectedComponentQuotientCongr_mk

On representatives, the quotient equivalence applies the original map.

Source context 4 commands

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

noncomputable section
namespace ClassFieldTheory
universe u v
variable {G : Type u} {H : Type v}
  [Group G] [Group H]
  [TopologicalSpace G] [TopologicalSpace H]
  [IsTopologicalGroup G] [IsTopologicalGroup H]
theorem connectedComponentQuotientCongr_mk
    (e : G ≃ₜ* H) (g : G) :
    connectedComponentQuotientCongr e
        (QuotientGroup.mk' (Subgroup.connectedComponentOfOne G) g) =
      QuotientGroup.mk' (Subgroup.connectedComponentOfOne H) (e g)