Module

MaximalIntersectionsAndSimpleRanks.lean

Nyll.ProCGroups.NormalSubgroups.MaximalIntersectionsAndSimpleRanks
1 declaration indexed from sourceView source ↗

Maximal normal subgroups and simple quotients

This module proves that a proper normal subgroup maximal among normal subgroups yields a simple quotient.

Declarations

ProCGroups.NormalSubgroups.maximal_normal_intersection_simple_quotient

A maximal normal subgroup gives a simple quotient.

Source context 4 commands

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

noncomputable section
open scoped Cardinal
namespace ProCGroups.NormalSubgroups
universe u
theorem maximal_normal_intersection_simple_quotient
    {G : Type u} [Group G] (M : Subgroup G) [M.Normal]
    (hproper : M ≠ ⊤)
    (hmax : ∀ N : Subgroup G, N.Normal → M < N → N = ⊤) :
    IsSimpleGroup (G ⧸ M)