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import OAI.Analysis.IrrationalRotation.Analysis.FieldUnboundedMultiplier
import OAI.Analysis.IrrationalRotation.Spectral.FieldDiagonalPolar
namespace OAI
noncomputable section
open MeasureTheory Filter
open scoped ENNReal ComplexOrder
namespace Invariant233.WeightedShift
variable {X : Type*} [MeasurableSpace X] {μ : Measure X}
private theorem resolventCoefficient_bound (t : ℝ) (ht : 0 ≤ t) :
‖((1 + t)⁻¹ : ℝ)‖ ≤ 1 := by
rw [Real.norm_eq_abs, abs_of_nonneg (inv_nonneg.mpr (by positivity))]
exact (inv_le_one₀ (by positivity)).mpr (by linarith)
def positiveResolventWeight (h : X → ℤ → ℝ) (hpos : ∀ x k, 0 ≤ h x k)
(x : X) : Weight :=
⟨fun k => (((1 + h x k)⁻¹ : ℝ) : ℂ), memℓp_infty <| by
refine ⟨1, ?_⟩
rintro r ⟨k, rfl⟩
simpa only [Complex.norm_real] using
resolventCoefficient_bound (h x k) (hpos x k)⟩
omit [MeasurableSpace X] in
private theorem positiveResolventWeight_bound
(h : X → ℤ → ℝ) (hpos : ∀ x k, 0 ≤ h x k) (x : X) :
‖positiveResolventWeight h hpos x‖ ≤ 1 := by
apply lp.norm_le_of_forall_le (by norm_num)
intro k
simpa only [positiveResolventWeight, Complex.norm_real] using
resolventCoefficient_bound (h x k) (hpos x k)
private theorem positiveResolventWeight_measurable
(h : X → ℤ → ℝ) (hpos : ∀ x k, 0 ≤ h x k)
(hm : ∀ k, AEStronglyMeasurable (fun x => h x k) μ) (k : ℤ) :
AEStronglyMeasurable (fun x => positiveResolventWeight h hpos x k) μ :=
Complex.continuous_ofReal.comp_aestronglyMeasurable (((hm k).const_add 1).inv₀)
def positiveFieldResolvent (h : X → ℤ → ℝ) (hpos : ∀ x k, 0 ≤ h x k)
(hm : ∀ k, AEStronglyMeasurable (fun x => h x k) μ) :
FieldHilbert μ →L[ℂ] FieldHilbert μ :=
fieldDiagonal (positiveResolventWeight h hpos) 1 (by norm_num)
(positiveResolventWeight_bound h hpos)
(positiveResolventWeight_measurable h hpos hm)
theorem positiveFieldResolvent_ae
(h : X → ℤ → ℝ) (hpos : ∀ x k, 0 ≤ h x k)
(hm : ∀ k, AEStronglyMeasurable (fun x => h x k) μ) (ξ : FieldHilbert μ) :
∀ᵐ x ∂μ, ∀ k,
positiveFieldResolvent h hpos hm ξ x k =
(((1 + h x k)⁻¹ : ℝ) : ℂ) * ξ x k :=
fieldDiagonal_coordinate_ae _ _ _ _ _ ξ
theorem positiveFieldResolvent_nonneg
(h : X → ℤ → ℝ) (hpos : ∀ x k, 0 ≤ h x k)
(hm : ∀ k, AEStronglyMeasurable (fun x => h x k) μ) :
0 ≤ positiveFieldResolvent h hpos hm := by
apply fieldDiagonal_nonneg
apply Eventually.of_forall
intro x k
change 0 ≤ ((((1 + h x k)⁻¹ : ℝ) : ℂ))
exact Complex.nonneg_iff.mpr
⟨inv_nonneg.mpr (add_nonneg (by norm_num) (hpos x k)), rfl⟩
theorem norm_positiveFieldResolvent_le
(h : X → ℤ → ℝ) (hpos : ∀ x k, 0 ≤ h x k)
(hm : ∀ k, AEStronglyMeasurable (fun x => h x k) μ) :
‖positiveFieldResolvent h hpos hm‖ ≤ 1 :=
norm_fieldDiagonal_le _ _ _ _ _
private theorem resolvent_scalar_identity (t : ℝ) (ht : 0 ≤ t) (z : ℂ) :
z - (((1 + t)⁻¹ : ℝ) : ℂ) * z =
(t : ℂ) * ((((1 + t)⁻¹ : ℝ) : ℂ) * z) := by
have hne : (1 + (t : ℂ)) ≠ 0 := by
exact_mod_cast (show (1 + t : ℝ) ≠ 0 by positivity)
push_cast
field_simp
ring
theorem positiveFieldResolvent_mem_domain
(h : X → ℤ → ℝ) (hpos : ∀ x k, 0 ≤ h x k)
(hm : ∀ k, AEStronglyMeasurable (fun x => h x k) μ) (ξ : FieldHilbert μ) :
positiveFieldResolvent h hpos hm ξ ∈
(fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ))).domain := by
apply (mem_fieldUnboundedMultiplier_domain_iff _ _).mpr
refine ⟨ξ - positiveFieldResolvent h hpos hm ξ, ?_⟩
filter_upwards [positiveFieldResolvent_ae h hpos hm ξ,
Lp.coeFn_sub ξ (positiveFieldResolvent h hpos hm ξ)] with x hR hsub
intro k
rw [hsub]
change ξ x k - positiveFieldResolvent h hpos hm ξ x k = _
rw [hR]
exact resolvent_scalar_identity (h x k) (hpos x k) (ξ x k)
theorem fieldUnboundedMultiplier_positiveFieldResolvent
(h : X → ℤ → ℝ) (hpos : ∀ x k, 0 ≤ h x k)
(hm : ∀ k, AEStronglyMeasurable (fun x => h x k) μ) (ξ : FieldHilbert μ) :
fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ))
⟨positiveFieldResolvent h hpos hm ξ,
positiveFieldResolvent_mem_domain h hpos hm ξ⟩ =
ξ - positiveFieldResolvent h hpos hm ξ := by
apply fieldUnboundedMultiplier_eq_of_ae
filter_upwards [positiveFieldResolvent_ae h hpos hm ξ,
Lp.coeFn_sub ξ (positiveFieldResolvent h hpos hm ξ)] with x hR hsub
intro k
rw [hsub]
change ξ x k - positiveFieldResolvent h hpos hm ξ x k = _
rw [hR]
exact resolvent_scalar_identity (h x k) (hpos x k) (ξ x k)
theorem positiveFieldResolvent_apply_add_multiplier
(h : X → ℤ → ℝ) (hpos : ∀ x k, 0 ≤ h x k)
(hm : ∀ k, AEStronglyMeasurable (fun x => h x k) μ)
(ξ : (fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ))).domain) :
positiveFieldResolvent h hpos hm
(ξ.val + fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ)) ξ) = ξ.val := by
apply fieldHilbert_ext
filter_upwards [positiveFieldResolvent_ae h hpos hm
(ξ.val + fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ)) ξ),
fieldUnboundedMultiplier_apply_ae (fun x k => (h x k : ℂ)) ξ,
Lp.coeFn_add ξ.val (fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ)) ξ)]
with x hR hH hadd
intro k
rw [hR, hadd]
change (((1 + h x k)⁻¹ : ℝ) : ℂ) *
(ξ.val x k + fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ)) ξ x k) = _
rw [hH]
have hne : (1 + (h x k : ℂ)) ≠ 0 := by
exact_mod_cast (show (1 + h x k : ℝ) ≠ 0 by
have := hpos x k
positivity)
push_cast
field_simp
theorem fieldUnboundedMultiplier_domain_eq_resolvent_range
(h : X → ℤ → ℝ) (hpos : ∀ x k, 0 ≤ h x k)
(hm : ∀ k, AEStronglyMeasurable (fun x => h x k) μ) :
(fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ))).domain =
LinearMap.range (positiveFieldResolvent h hpos hm).toLinearMap := by
ext ξ
constructor
· intro hξ
exact ⟨ξ + fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ)) ⟨ξ, hξ⟩,
positiveFieldResolvent_apply_add_multiplier h hpos hm ⟨ξ, hξ⟩⟩
· rintro ⟨η, rfl⟩
exact positiveFieldResolvent_mem_domain h hpos hm η
theorem fieldUnboundedMultiplier_domain_invariant_of_commute_resolvent
(h : X → ℤ → ℝ) (hpos : ∀ x k, 0 ≤ h x k)
(hm : ∀ k, AEStronglyMeasurable (fun x => h x k) μ)
(A : FieldHilbert μ →L[ℂ] FieldHilbert μ)
(hA : Commute A (positiveFieldResolvent h hpos hm))
(ξ : (fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ))).domain) :
A ξ.val ∈ (fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ))).domain := by
apply (fieldUnboundedMultiplier_domain_eq_resolvent_range h hpos hm).ge
refine ⟨A (ξ.val + fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ)) ξ), ?_⟩
have heq := congrArg (fun B : FieldHilbert μ →L[ℂ] FieldHilbert μ =>
B (ξ.val + fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ)) ξ)) hA.eq
change positiveFieldResolvent h hpos hm
(A (ξ.val + fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ)) ξ)) = A ξ.val
change A (positiveFieldResolvent h hpos hm
(ξ.val + fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ)) ξ)) =
positiveFieldResolvent h hpos hm
(A (ξ.val + fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ)) ξ)) at heq
rw [← heq, positiveFieldResolvent_apply_add_multiplier h hpos hm ξ]
theorem fieldUnboundedMultiplier_commutes_of_commute_resolvent
(h : X → ℤ → ℝ) (hpos : ∀ x k, 0 ≤ h x k)
(hm : ∀ k, AEStronglyMeasurable (fun x => h x k) μ)
(A : FieldHilbert μ →L[ℂ] FieldHilbert μ)
(hA : Commute A (positiveFieldResolvent h hpos hm))
(ξ : (fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ))).domain) :
fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ))
⟨A ξ.val,
fieldUnboundedMultiplier_domain_invariant_of_commute_resolvent h hpos hm A hA ξ⟩ =
A (fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ)) ξ) := by
let η := ξ.val + fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ)) ξ
have hRη : positiveFieldResolvent h hpos hm η = ξ.val :=
positiveFieldResolvent_apply_add_multiplier h hpos hm ξ
have hRA : positiveFieldResolvent h hpos hm (A η) = A ξ.val := by
have heq := congrArg (fun B : FieldHilbert μ →L[ℂ] FieldHilbert μ => B η) hA.eq
change A (positiveFieldResolvent h hpos hm η) =
positiveFieldResolvent h hpos hm (A η) at heq
exact heq.symm.trans (congrArg A hRη)
have hξ : (⟨A ξ.val,
fieldUnboundedMultiplier_domain_invariant_of_commute_resolvent h hpos hm A hA ξ⟩ :
(fieldUnboundedMultiplier μ (fun x k => (h x k : ℂ))).domain) =
⟨positiveFieldResolvent h hpos hm (A η),
positiveFieldResolvent_mem_domain h hpos hm (A η)⟩ :=
Subtype.ext hRA.symm
rw [hξ, fieldUnboundedMultiplier_positiveFieldResolvent, hRA]
dsimp [η]
rw [map_add, add_sub_cancel_left]
end Invariant233.WeightedShift
end
end OAI