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import OAI.Analysis.FreeGroupFactor.MomentFlow
namespace OAI
namespace FreeGroupFactorMain
noncomputable section
universe uG uH
open Set Metric Filter
open scoped NNReal Topology BigOperators ContDiff
open scoped ComplexConjugate
abbrev deltaOne {G : Type uG} [Group G] : GroupHilbert G := by
classical
exact lp.single 2 1 1
theorem deltaOne_eq {G : Type uG} [Group G] [DecidableEq G] :
(deltaOne : GroupHilbert G) = lp.single 2 1 1 := by
ext x
simp [deltaOne, lp.single_apply, Pi.single_apply]
theorem groupVN_matrix {G : Type uG} [Group G] [DecidableEq G]
(T : groupVonNeumann G) (x y : G) :
((T : GroupOperator G) (lp.single 2 y 1)) x =
((T : GroupOperator G) deltaOne) (x * y⁻¹) := by
have hr : rightRegular y⁻¹ deltaOne = lp.single 2 y 1 := by
ext b
simp [deltaOne, lp.single_apply, Pi.single_apply, mul_inv_eq_one]
rw [← hr]
have hc := congrArg (fun f : GroupOperator G => f deltaOne)
(groupVN_commute_right T y⁻¹)
simpa only [mul_apply_eq_comp, rightRegular_apply] using
congrArg (fun v : GroupHilbert G => v x) hc.symm
theorem groupVN_star_coefficient {G : Type uG} [Group G] [DecidableEq G]
(T : groupVonNeumann G) (x : G) :
((star T : GroupOperator G) deltaOne) x =
conj (((T : GroupOperator G) deltaOne) x⁻¹) := by
calc
((star T : GroupOperator G) deltaOne) x =
inner ℂ (lp.single 2 x (1 : ℂ)) ((star T : GroupOperator G) deltaOne) := by
simp only [lp.inner_single_left, RCLike.inner_apply, map_one, mul_one]
_ = inner ℂ ((T : GroupOperator G) (lp.single 2 x 1)) deltaOne := by
exact ContinuousLinearMap.adjoint_inner_right _ _ _
_ = conj (((T : GroupOperator G) (lp.single 2 x 1)) 1) := by
simp only [deltaOne, lp.inner_single_right, RCLike.inner_apply, one_mul]
_ = _ := by rw [groupVN_matrix]; simp
theorem canonicalTrace_star_mul_inner {G : Type uG} [Group G] [DecidableEq G]
(T U : groupVonNeumann G) :
canonicalTrace (star T * U) = inner ℂ
((T : GroupOperator G) deltaOne) ((U : GroupOperator G) deltaOne) := by
classical
rw [canonicalTrace_eq_inner, ← deltaOne_eq]
change inner ℂ deltaOne (star (T : GroupOperator G) ((U : GroupOperator G) deltaOne)) = _
rw [ContinuousLinearMap.star_eq_adjoint, ContinuousLinearMap.adjoint_inner_right]
theorem canonicalTrace_mul {G : Type uG} [Group G] [DecidableEq G]
(T U : groupVonNeumann G) : canonicalTrace (T * U) = canonicalTrace (U * T) := by
have he (T U : groupVonNeumann G) :
canonicalTrace (T * U) = ∑' x : G,
((T : GroupOperator G) deltaOne) x⁻¹ * ((U : GroupOperator G) deltaOne) x := by
rw [← star_star T, canonicalTrace_star_mul_inner]
change (∑' x, inner ℂ (((star T : GroupOperator G) deltaOne) x)
(((U : GroupOperator G) deltaOne) x)) = _
apply tsum_congr
intro x
rw [groupVN_star_coefficient]
simp [RCLike.inner_apply, mul_comm]
rw [he, he]
simpa only [Equiv.inv_apply, inv_inv, mul_comm] using
((Equiv.inv G).tsum_eq (fun x =>
((T : GroupOperator G) deltaOne) x⁻¹ * ((U : GroupOperator G) deltaOne) x)).symm
def hilbertSequenceMap {G : Type uG} {H : Type uH} (e : GroupHilbert G ≃ₗᵢ[ℂ] GroupHilbert H)
(ξ : lp (fun _ : ℕ => GroupHilbert G) 2) :
lp (fun _ : ℕ => GroupHilbert H) 2 :=
⟨fun n => e (ξ n), Memℓp.of_norm (by simpa only [e.norm_map] using (lp.memℓp ξ).norm)⟩
theorem spatial_ultraweak_continuous {G : Type uG} {H : Type uH}
(e : GroupHilbert G ≃ₗᵢ[ℂ] GroupHilbert H) :
@Continuous _ _ (ultraweakOperatorTopology G) (ultraweakOperatorTopology H)
e.conjStarAlgEquiv := by
apply continuous_iInf_rng.mpr
intro ξ
apply continuous_iInf_rng.mpr
intro η
apply continuous_induced_rng.mpr
have heq :
(fun T : GroupOperator G => ∑' k : ℕ, inner ℂ (η k) (e.conjStarAlgEquiv T (ξ k))) =
(fun T : GroupOperator G => ∑' k : ℕ,
inner ℂ (hilbertSequenceMap e.symm η k) (T (hilbertSequenceMap e.symm ξ k))) := by
funext T
apply tsum_congr
intro k
change inner ℂ (η k) (e (T (e.symm (ξ k)))) =
inner ℂ (e.symm (η k)) (T (e.symm (ξ k)))
rw [← e.inner_map_map]
simp
change @Continuous _ _ (ultraweakOperatorTopology G) _
(fun T : GroupOperator G => ∑' k : ℕ, inner ℂ (η k) (e.conjStarAlgEquiv T (ξ k)))
rw [heq]
exact continuous_iInf_dom (i := hilbertSequenceMap e.symm ξ)
(continuous_iInf_dom (i := hilbertSequenceMap e.symm η) continuous_induced_dom)
def spatialGroupIso {G : Type uG} {H : Type uH} [Group G] [Group H]
(e : GroupHilbert G ≃ₗᵢ[ℂ] GroupHilbert H)
(hVN : ∀ T : GroupOperator G,
T ∈ groupVonNeumann G ↔ e.conjStarAlgEquiv T ∈ groupVonNeumann H) :
groupVonNeumann G ≃⋆ₐ[ℂ] groupVonNeumann H where
toFun T := ⟨e.conjStarAlgEquiv T, (hVN T).mp T.property⟩
invFun T := ⟨e.conjStarAlgEquiv.symm T, (hVN _).mpr (by rw [e.conjStarAlgEquiv.apply_symm_apply]; exact T.property)⟩
left_inv T := Subtype.ext (e.conjStarAlgEquiv.symm_apply_apply T)
right_inv T := Subtype.ext (e.conjStarAlgEquiv.apply_symm_apply T)
map_mul' T U := Subtype.ext (map_mul e.conjStarAlgEquiv (T : GroupOperator G) (U : GroupOperator G))
map_add' T U := Subtype.ext (map_add e.conjStarAlgEquiv (T : GroupOperator G) (U : GroupOperator G))
map_star' T := Subtype.ext (map_star e.conjStarAlgEquiv (T : GroupOperator G))
map_smul' c T := Subtype.ext (map_smul e.conjStarAlgEquiv c (T : GroupOperator G))
theorem spatialGroupIso_normal {G : Type uG} {H : Type uH} [Group G] [Group H]
(e : GroupHilbert G ≃ₗᵢ[ℂ] GroupHilbert H)
(hVN : ∀ T : GroupOperator G,
T ∈ groupVonNeumann G ↔ e.conjStarAlgEquiv T ∈ groupVonNeumann H) :
@Continuous _ _ (groupUltraweakTopology G) (groupUltraweakTopology H)
(spatialGroupIso e hVN) := by
let : TopologicalSpace (GroupOperator G) := ultraweakOperatorTopology G
let : TopologicalSpace (GroupOperator H) := ultraweakOperatorTopology H
let : TopologicalSpace (groupVonNeumann G) := groupUltraweakTopology G
let : TopologicalSpace (groupVonNeumann H) := groupUltraweakTopology H
apply continuous_induced_rng.mpr
have hinc : Continuous (fun T : groupVonNeumann G => (T : GroupOperator G)) :=
continuous_induced_dom
exact (spatial_ultraweak_continuous e).comp hinc
theorem normalTracialIso_of_spatial {G : Type uG} {H : Type uH} [Group G] [Group H]
(e : GroupHilbert G ≃ₗᵢ[ℂ] GroupHilbert H)
(hδ : e deltaOne = deltaOne)
(hVN : ∀ T : GroupOperator G,
T ∈ groupVonNeumann G ↔ e.conjStarAlgEquiv T ∈ groupVonNeumann H) :
HasNormalTracialIso G H := by
classical
refine ⟨spatialGroupIso e hVN, fun T => ?_, spatialGroupIso_normal e hVN⟩
rw [canonicalTrace_eq_inner, canonicalTrace_eq_inner]
change inner ℂ deltaOne (e ((T : GroupOperator G) (e.symm deltaOne))) =
inner ℂ deltaOne ((T : GroupOperator G) deltaOne)
rw [← hδ, e.symm_apply_apply, e.inner_map_map]
open scoped ComplexConjugate ENNReal
theorem operator_matrix_ext {G : Type uG} [DecidableEq G] (T U : GroupOperator G)
(h : ∀ g, T (lp.single 2 g 1) = U (lp.single 2 g 1)) : T = U := by
classical
apply ContinuousLinearMap.ext
intro ξ
have hT := (lp.hasSum_single (by norm_num : (2 : ℝ≥0∞) ≠ ⊤) ξ).mapL T
have hU := (lp.hasSum_single (by norm_num : (2 : ℝ≥0∞) ≠ ⊤) ξ).mapL U
have he (g : G) : T (lp.single 2 g (ξ g)) = U (lp.single 2 g (ξ g)) := by
have hc : lp.single (E := fun _ : G => ℂ) 2 g (ξ g) =
(ξ g) • lp.single (E := fun _ : G => ℂ) 2 g 1 := by
ext b
simp [lp.single_apply, Pi.single_apply]
rw [hc, map_smul, map_smul, h]
simp only [he] at hT
exact hT.unique hU
theorem operator_coeff_tsum {G : Type uG} [DecidableEq G] (T : GroupOperator G)
(ξ : GroupHilbert G) (x : G) :
(T ξ) x = ∑' y : G, (T (lp.single 2 y 1)) x * ξ y := by
calc
(T ξ) x = inner ℂ (lp.single 2 x 1) (T ξ) := by simp [lp.inner_single_left]
_ = inner ℂ (star T (lp.single 2 x 1)) ξ := by
rw [ContinuousLinearMap.star_eq_adjoint, ContinuousLinearMap.adjoint_inner_left]
_ = ∑' y : G, (T (lp.single 2 y 1)) x * ξ y := by
rw [lp.inner_eq_tsum]
apply tsum_congr
intro y
have he : conj ((star T (lp.single 2 x 1)) y) = (T (lp.single 2 y 1)) x := by
calc
_ = inner ℂ (star T (lp.single 2 x 1)) (lp.single 2 y 1) := by
simp [lp.inner_single_right]
_ = inner ℂ (lp.single 2 x 1) (T (lp.single 2 y 1)) := by
rw [ContinuousLinearMap.star_eq_adjoint, ContinuousLinearMap.adjoint_inner_left]
_ = _ := by simp [lp.inner_single_left]
simp only [RCLike.inner_apply, he, mul_comm]
theorem matrix_of_commute_right {G : Type uG} [Group G] [DecidableEq G]
(T : GroupOperator G) (hT : ∀ g, rightRegular g * T = T * rightRegular g)
(x y : G) :
(T (lp.single 2 y 1)) x = (T deltaOne) (x * y⁻¹) := by
have hr : rightRegular y⁻¹ deltaOne = lp.single 2 y 1 := by
ext b
simp [deltaOne, lp.single_apply, Pi.single_apply, mul_inv_eq_one]
rw [← hr]
have hc := congrArg (fun f : GroupOperator G => f deltaOne) (hT y⁻¹)
simpa only [mul_apply_eq_comp, rightRegular_apply] using
congrArg (fun v : GroupHilbert G => v x) hc.symm
theorem matrix_of_commute_left {G : Type uG} [Group G] [DecidableEq G]
(T : GroupOperator G) (hT : ∀ g, leftRegular g * T = T * leftRegular g)
(x y : G) :
(T (lp.single 2 y 1)) x = (T deltaOne) (y⁻¹ * x) := by
have hl : leftRegular y deltaOne = lp.single 2 y 1 := by
ext b
simp [deltaOne, lp.single_apply, Pi.single_apply, inv_mul_eq_one, eq_comm]
rw [← hl]
have hc := congrArg (fun f : GroupOperator G => f deltaOne) (hT y)
simpa only [mul_apply_eq_comp, leftRegular_apply] using
congrArg (fun v : GroupHilbert G => v x) hc.symm
theorem mem_groupVN_iff_commute_right {G : Type uG} [Group G]
(T : GroupOperator G) : T ∈ groupVonNeumann G ↔
∀ g, rightRegular g * T = T * rightRegular g := by
classical
refine ⟨fun h g => groupVN_commute_right ⟨T,h⟩ g, ?_⟩
intro hT
have hc (U : GroupOperator G) (hU : ∀ g, leftRegular g * U = U * leftRegular g) :
U * T = T * U := by
apply operator_matrix_ext
intro k
ext x
have hleft : ((U * T) (lp.single 2 k 1)) x =
∑' y : G, (U deltaOne) (y⁻¹ * x) * (T deltaOne) (y * k⁻¹) := by
change (U (T (lp.single 2 k 1))) x = _
rw [operator_coeff_tsum U]
apply tsum_congr
intro y
rw [matrix_of_commute_left U hU x y, matrix_of_commute_right T hT y k]
have hright : ((T * U) (lp.single 2 k 1)) x =
∑' y : G, (T deltaOne) (x * y⁻¹) * (U deltaOne) (k⁻¹ * y) := by
change (T (U (lp.single 2 k 1))) x = _
rw [operator_coeff_tsum T]
apply tsum_congr
intro y
rw [matrix_of_commute_right T hT x y, matrix_of_commute_left U hU y k]
rw [hleft, hright]
let e : G ≃ G := ((Equiv.inv G).trans (Equiv.mulLeft x)).trans (Equiv.mulRight k)
have hs := e.tsum_eq (fun y => (U deltaOne) (y⁻¹ * x) * (T deltaOne) (y * k⁻¹))
change (∑' c : G, (U deltaOne) ((x * c⁻¹ * k)⁻¹ * x) *
(T deltaOne) (x * c⁻¹ * k * k⁻¹)) = _ at hs
simpa only [mul_inv_rev, inv_inv, mul_assoc, inv_mul_cancel,
mul_inv_cancel, mul_one, mul_comm] using hs.symm
rw [groupVonNeumann, StarSubalgebra.mem_centralizer_iff]
intro U hU
have hu : ∀ g, leftRegular g * U = U * leftRegular g := by
intro g
exact ((StarSubalgebra.mem_centralizer_iff ℂ).mp hU _
(leftRegular_mem_leftTranslations g)).1
refine ⟨hc U hu, hc (star U) ?_⟩
intro g
have hh := congrArg star (hu g⁻¹)
simpa only [star_mul, leftRegular_star, inv_inv] using hh.symm
open scoped ComplexConjugate
theorem rightRegular_single {G : Type uG} [Group G] [DecidableEq G] (g y : G) :
rightRegular g (lp.single 2 y (1 : ℂ)) = lp.single 2 (y * g⁻¹) 1 := by
ext x
simp only [rightRegular_apply, lp.single_apply, Pi.single_apply]
congr 1
exact propext (eq_mul_inv_iff_mul_eq.symm)
theorem mem_groupVN_of_matrix_invariant {G : Type uG} [Group G] [DecidableEq G]
(T : GroupOperator G)
(hT : ∀ x y g : G, (T (lp.single 2 (y*g) 1)) (x*g) =
(T (lp.single 2 y 1)) x) : T ∈ groupVonNeumann G := by
rw [mem_groupVN_iff_commute_right]
intro g
apply operator_matrix_ext
intro y
ext x
simp only [mul_apply_eq_comp, rightRegular_apply]
change (T (lp.single 2 y 1)) (x*g) = (T (rightRegular g (lp.single 2 y 1))) x
rw [rightRegular_single]
simpa only [mul_inv_cancel_right] using (hT (x*g) y g⁻¹).symm
theorem haar_orbit_orthonormal {G : Type uG} {H : Type uH} [Group G] [Group H] [DecidableEq G]
(ρ : G →* groupVonNeumann H)
(hstar : ∀ g, star (ρ g) = ρ g⁻¹)
(htrace : ∀ g, canonicalTrace (ρ g) = if g = 1 then 1 else 0) :
Orthonormal ℂ (fun g => ((ρ g : groupVonNeumann H) : GroupOperator H) deltaOne) := by
classical
rw [orthonormal_iff_ite]
intro x y
rw [← canonicalTrace_star_mul_inner, hstar, ← map_mul, htrace]
simp only [inv_mul_eq_one]
theorem spatial_of_haar_total {G : Type uG} {H : Type uH} [Group G] [Group H] [DecidableEq G]
(ρ : G →* groupVonNeumann H)
(hstar : ∀ g, star (ρ g) = ρ g⁻¹)
(htrace : ∀ g, canonicalTrace (ρ g) = if g = 1 then 1 else 0)
(htotal : ⊤ ≤ (Submodule.span ℂ (Set.range
(fun g => ((ρ g : groupVonNeumann H) : GroupOperator H) deltaOne))).topologicalClosure) :
∃ e : GroupHilbert G ≃ₗᵢ[ℂ] GroupHilbert H,
e deltaOne = deltaOne ∧
(∀ g, e.conjStarAlgEquiv (leftRegular g) = (ρ g : GroupOperator H)) ∧
∀ T : GroupOperator G, T ∈ groupVonNeumann G ↔
e.conjStarAlgEquiv T ∈ groupVonNeumann H := by
classical
let v : G → GroupHilbert H := fun g => ((ρ g : groupVonNeumann H) : GroupOperator H) deltaOne
have hon : Orthonormal ℂ v := haar_orbit_orthonormal ρ hstar htrace
let e : GroupHilbert G ≃ₗᵢ[ℂ] GroupHilbert H :=
(hon.isHilbertSum htotal).linearIsometryEquiv.symm
have he (g : G) : e (lp.single 2 g 1) = v g :=
hon.linearIsometryEquiv_symm_apply_single_one htotal g
have hδ : e deltaOne = deltaOne := by
rw [deltaOne_eq, he]
simp [v]
have hleft (g : G) : e.conjStarAlgEquiv (leftRegular g) = (ρ g : GroupOperator H) := by
apply e.conjStarAlgEquiv.symm.injective
change e.conjStarAlgEquiv.symm (e.conjStarAlgEquiv (leftRegular g)) =
e.conjStarAlgEquiv.symm (ρ g : GroupOperator H)
rw [e.conjStarAlgEquiv.symm_apply_apply]
apply operator_matrix_ext
intro y
apply e.injective
change e (leftRegular g (lp.single 2 y 1)) =
e (e.symm ((ρ g : GroupOperator H) (e (lp.single 2 y 1))))
rw [e.apply_symm_apply, he]
have hl : leftRegular g (lp.single 2 y (1 : ℂ)) = lp.single 2 (g*y) 1 := by
ext x
simp only [leftRegular_apply, lp.single_apply, Pi.single_apply]
congr 1
exact propext (inv_mul_eq_iff_eq_mul)
rw [hl, he]
change ((ρ (g*y) : groupVonNeumann H) : GroupOperator H) deltaOne = _
rw [map_mul]
rfl
refine ⟨e, hδ, hleft, ?_⟩
intro T
constructor
· intro hT
rw [mem_groupVN_iff_commute_right]
intro g
apply e.conjStarAlgEquiv.symm.injective
change e.conjStarAlgEquiv.symm (rightRegular g * e.conjStarAlgEquiv T) =
e.conjStarAlgEquiv.symm (e.conjStarAlgEquiv T * rightRegular g)
rw [map_mul, map_mul, e.conjStarAlgEquiv.symm_apply_apply]
have hc : e.conjStarAlgEquiv.symm (rightRegular g) ∈
StarSubalgebra.centralizer ℂ (leftTranslations G) := by
rw [StarSubalgebra.mem_centralizer_iff, leftTranslations_eq_range]
rintro _ ⟨x,rfl⟩
constructor
· apply e.conjStarAlgEquiv.injective
change e.conjStarAlgEquiv (leftRegular _ * e.conjStarAlgEquiv.symm (rightRegular g)) =
e.conjStarAlgEquiv (e.conjStarAlgEquiv.symm (rightRegular g) * leftRegular _)
rw [map_mul, map_mul, e.conjStarAlgEquiv.apply_symm_apply, hleft]
exact (groupVN_commute_right (ρ x) g).symm
· rw [leftRegular_star]
apply e.conjStarAlgEquiv.injective
change e.conjStarAlgEquiv (leftRegular _ * e.conjStarAlgEquiv.symm (rightRegular g)) =
e.conjStarAlgEquiv (e.conjStarAlgEquiv.symm (rightRegular g) * leftRegular _)
rw [map_mul, map_mul, e.conjStarAlgEquiv.apply_symm_apply, hleft]
exact (groupVN_commute_right (ρ x⁻¹) g).symm
exact ((StarSubalgebra.mem_centralizer_iff ℂ).mp hT _ hc).1
· intro hT
let U : groupVonNeumann H := ⟨e.conjStarAlgEquiv T, hT⟩
have hm (x y : G) : (T (lp.single 2 y 1)) x =
canonicalTrace (star (ρ x) * U * ρ y) := by
calc
(T (lp.single 2 y 1)) x = inner ℂ (lp.single 2 x 1) (T (lp.single 2 y 1)) := by
simp [lp.inner_single_left]
_ = inner ℂ (v x) ((U : GroupOperator H) (v y)) := by
rw [← he x, ← he y, ← e.inner_map_map]
change inner ℂ (e (lp.single 2 x 1)) (e (T (lp.single 2 y 1))) =
inner ℂ (e (lp.single 2 x 1)) (e (T (e.symm (e (lp.single 2 y 1)))))
rw [e.symm_apply_apply]
_ = canonicalTrace (star (ρ x) * U * ρ y) := by
rw [mul_assoc, canonicalTrace_star_mul_inner]
rfl
apply mem_groupVN_of_matrix_invariant T
intro x y g
rw [hm, hm, map_mul, map_mul, star_mul]
have hc := canonicalTrace_mul (star (ρ g) * star (ρ x) * U * ρ y) (ρ g)
simp only [← mul_assoc]
rw [hc]
simp only [hstar, ← mul_assoc, ← map_mul, mul_inv_cancel, one_mul]
theorem normalTracialIso_of_haar_total {G : Type uG} {H : Type uH} [Group G] [Group H] [DecidableEq G]
(ρ : G →* groupVonNeumann H)
(hstar : ∀ g, star (ρ g) = ρ g⁻¹)
(htrace : ∀ g, canonicalTrace (ρ g) = if g = 1 then 1 else 0)
(htotal : ⊤ ≤ (Submodule.span ℂ (Set.range
(fun g => ((ρ g : groupVonNeumann H) : GroupOperator H) deltaOne))).topologicalClosure) :
HasNormalTracialIso G H := by
obtain ⟨e,hδ,_hρ,hVN⟩ := spatial_of_haar_total ρ hstar htrace htotal
exact normalTracialIso_of_spatial e hδ hVN
theorem iso_extension_of_haar_total {G : Type uG} {H : Type uH} [Group G] [Group H] [DecidableEq G]
(ρ : G →* groupVonNeumann H)
(hstar : ∀ g, star (ρ g) = ρ g⁻¹)
(htrace : ∀ g, canonicalTrace (ρ g) = if g = 1 then 1 else 0)
(htotal : ⊤ ≤ (Submodule.span ℂ (Set.range
(fun g => ((ρ g : groupVonNeumann H) : GroupOperator H) deltaOne))).topologicalClosure) :
∃ Φ : groupVonNeumann G ≃⋆ₐ[ℂ] groupVonNeumann H,
(∀ T, canonicalTrace (Φ T) = canonicalTrace T) ∧
@Continuous _ _ (groupUltraweakTopology G) (groupUltraweakTopology H) Φ ∧
∀ g, Φ (groupUnitary g) = ρ g := by
classical
obtain ⟨e,hδ,hρ,hVN⟩ := spatial_of_haar_total ρ hstar htrace htotal
refine ⟨spatialGroupIso e hVN, ?_, spatialGroupIso_normal e hVN, ?_⟩
· intro T
rw [canonicalTrace_eq_inner, canonicalTrace_eq_inner, ← deltaOne_eq, ← deltaOne_eq]
change inner ℂ deltaOne (e ((T : GroupOperator G) (e.symm deltaOne))) =
inner ℂ deltaOne ((T : GroupOperator G) deltaOne)
rw [← hδ, e.symm_apply_apply, e.inner_map_map]
· intro g
apply Subtype.ext
exact hρ g
end
end FreeGroupFactorMain
end OAI