import Mathlib import OAI.GroupTheory.SimpleAmenable.PolygonGeometry.SmallControlTransfer import OAI.GroupTheory.SimpleAmenable.PolygonGeometry.InvariantPatching namespace OAI section section open scoped symmDiff namespace SimpleAmenable open scoped commutatorElement open scoped commutatorElement section ControlledPatching variable {α H ι : Type*} [Fintype α] [DecidableEq α] [Group H] [Group.IsPerfect (alternatingGroup α)] theorem controlled_cell_normalizes (L : Finset α → Subgroup H) (c : alternatingGroup α →* H) (hc : ∀ σ I, ∀ x ∈ L I, c σ*x*(c σ)⁻¹ ∈ L (I.map σ.val.toEmbedding)) (hd : ∀ I J, Disjoint I J → ∀ x ∈ L I, ∀ y ∈ L J, Commute x y) (hα : 20 ≤ Fintype.card α) (F p v : ι → TrackStar α →* H) (j k : TrackStar α →* H) (hp : ∀ i, SmallSupported L (p i)) (hv : ∀ i, SmallSupported L (v i)) (hj : SmallSupported L j) (hpc : ∀ i, SmallControlled c (p i) j) (hvc : ∀ i, SmallControlled c (v i) k) (hjk : ∀ s t, Commute (j s) (k t)) (hsplit : ∀ i s, F i s=p i s*v i s) : ∀ i s, F i s ∈ Subgroup.normalizer ((⨆ i, (p i).range : Subgroup H) : Set H) := by have hcomm (i i' : ι) (s t : TrackStar α) : Commute (p i s) (v i' t) := small_control_disjoint L c hc hd hα _ _ _ _ (hp i) (hv i') hj (hpc i) (hvc i') hjk s t have ho (i : ι) (s : TrackStar α) : v i s ∈ Subgroup.centralizer ((⨆ i, (p i).range : Subgroup H) : Set H) := by have hle : (⨆ i, (p i).range : Subgroup H) ≤ Subgroup.centralizer ({v i s} : Set H) := by apply iSup_le rintro i' x ⟨t,rfl⟩ y hy obtain rfl := Set.mem_singleton_iff.mp hy exact (hcomm i' i t s).eq.symm intro x hx exact (hle hx _ rfl).symm intro i s exact normalizes_of_cell_split _ _ _ _ (hsplit i s) ((le_iSup (fun i => (p i).range) i) ⟨s,rfl⟩) (ho i s) theorem sameActionOn_iSup {D : Type*} (f g : D → H) (P : ι → Subgroup H) (h : ∀ i, SameActionOn f g (P i)) : SameActionOn f g (⨆ i, P i) := by intro d x hx let F : H →* H := (MulAut.conj (f d)).toMonoidHom let J : H →* H := (MulAut.conj (g d)).toMonoidHom have hle : (⨆ i, P i) ≤ F.eqLocus J := by apply iSup_le intro i y hy exact h i d y hy exact hle hx end ControlledPatching end SimpleAmenable end end end OAI