Module

Quasifree.lean

Nyll.ProCGroups.FreeProC.Characterization.Quasifree
3 declarations indexed from sourceView source ↗

Pro C Groups / Free pro-C / Characterization / Quasifree

This module formulates quasifree proper-solution growth and its cardinal monotonicity consequences.

Declarations

ProCGroups.FreeProC.Characterization.HasTopologicalGeneratingSetOfCardinality

A topological group has a topological generating set of cardinality \(\kappa\).

Source context 4 commands

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

noncomputable section
open scoped Cardinal
namespace ProCGroups.FreeProC.Characterization
universe u
def HasTopologicalGeneratingSetOfCardinality
    (G : Type u) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
    (κ : Cardinal) : Prop
ProCGroups.FreeProC.Characterization.HasQuasifreeProperSolutionProperty

A group has the quasifree proper-solution property at rank \(\kappa\) for finite split \(C\)-embedding problems.

Source context 4 commands

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

noncomputable section
open scoped Cardinal
namespace ProCGroups.FreeProC.Characterization
universe u
def HasQuasifreeProperSolutionProperty
    (C : ProCGroups.FiniteGroupClass.{u})
    (G : Type u) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
    (κ : Cardinal) : Prop
ProCGroups.FreeProC.Characterization.IsQuasifreeOfRank

Quasifreeness at infinite rank \(\kappa\). The rank field is deliberately topological: in profinite contexts an abstract generating set is too weak and does not control the closed subgroup generated by the chosen family. The lifting field records the standard proper-solution condition for finite split embedding problems.

Source context 4 commands

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

noncomputable section
open scoped Cardinal
namespace ProCGroups.FreeProC.Characterization
universe u
def IsQuasifreeOfRank (C : ProCGroups.FiniteGroupClass.{u})
    (G : Type u) [Group G] [TopologicalSpace G] [IsTopologicalGroup G]
    [CompactSpace G] [T2Space G] [TotallyDisconnectedSpace G]
    (κ : Cardinal) : Prop