nevanlinna/Nevanlinna/holomorphic_JensenFormula2....

450 lines
12 KiB
Plaintext
Raw Normal View History

2024-08-12 13:05:55 +02:00
import Mathlib.Analysis.Complex.CauchyIntegral
2024-08-21 17:04:45 +02:00
import Mathlib.Analysis.Analytic.IsolatedZeros
import Nevanlinna.analyticOn_zeroSet
2024-08-12 13:05:55 +02:00
import Nevanlinna.harmonicAt_examples
import Nevanlinna.harmonicAt_meanValue
2024-08-22 13:09:03 +02:00
import Nevanlinna.specialFunctions_CircleIntegral_affine
2024-08-12 13:05:55 +02:00
2024-08-21 17:04:45 +02:00
open Real
2024-08-22 14:52:52 +02:00
2024-08-12 13:05:55 +02:00
2024-08-21 17:04:45 +02:00
theorem jensen_case_R_eq_one
2024-08-12 13:05:55 +02:00
(f : )
2024-09-11 15:48:43 +02:00
(h₁f : AnalyticOn f (Metric.closedBall 0 1))
2024-08-21 17:04:45 +02:00
(h₂f : f 0 ≠ 0) :
2024-09-11 11:09:03 +02:00
log ‖f 0‖ = -∑ᶠ s, (h₁f.order s).toNat * log (‖s.1‖⁻¹) + (2 * π)⁻¹ * ∫ (x : ) in (0)..(2 * π), log ‖f (circleMap 0 1 x)‖ := by
have h₁U : IsPreconnected (Metric.closedBall (0 : ) 1) :=
(convex_closedBall (0 : ) 1).isPreconnected
have h₂U : IsCompact (Metric.closedBall (0 : ) 1) :=
isCompact_closedBall 0 1
2024-08-21 17:04:45 +02:00
2024-09-10 15:29:30 +02:00
have h'₂f : ∃ u ∈ (Metric.closedBall (0 : ) 1), f u ≠ 0 := by
2024-09-10 16:50:29 +02:00
use 0; simp; exact h₂f
2024-09-10 15:29:30 +02:00
2024-09-11 11:09:03 +02:00
obtain ⟨F, h₁F, h₂F, h₃F⟩ := AnalyticOnCompact.eliminateZeros₂ h₁U h₂U h₁f h'₂f
2024-08-21 17:04:45 +02:00
2024-09-10 15:29:30 +02:00
have h'₁F : ∀ z ∈ Metric.closedBall (0 : ) 1, HolomorphicAt F z := by
2024-09-11 10:24:45 +02:00
intro z h₁z
apply AnalyticAt.holomorphicAt
exact h₁F z h₁z
2024-09-10 15:29:30 +02:00
2024-09-11 11:09:03 +02:00
let G := fun z ↦ log ‖F z‖ + ∑ s ∈ (finiteZeros h₁U h₂U h₁f h'₂f).toFinset, (h₁f.order s).toNat * log ‖z - s‖
2024-08-21 17:04:45 +02:00
have decompose_f : ∀ z ∈ Metric.closedBall (0 : ) 1, f z ≠ 0 → log ‖f z‖ = G z := by
intro z h₁z h₂z
conv =>
left
arg 1
rw [h₃F]
2024-09-10 15:29:30 +02:00
rw [smul_eq_mul]
2024-08-21 17:04:45 +02:00
rw [norm_mul]
rw [norm_prod]
2024-09-10 15:29:30 +02:00
left
2024-08-21 17:04:45 +02:00
arg 2
intro b
rw [norm_pow]
simp only [Complex.norm_eq_abs, Finset.univ_eq_attach]
rw [Real.log_mul]
rw [Real.log_prod]
conv =>
left
2024-09-10 15:29:30 +02:00
left
2024-08-21 17:04:45 +02:00
arg 2
intro s
rw [Real.log_pow]
dsimp [G]
2024-09-10 15:29:30 +02:00
abel
2024-08-21 17:04:45 +02:00
2024-09-10 16:50:29 +02:00
-- ∀ x ∈ ⋯.toFinset, Complex.abs (z - ↑x) ^ (h'₁f.order x).toNat ≠ 0
2024-09-11 11:09:03 +02:00
have : ∀ x ∈ (finiteZeros h₁U h₂U h₁f h'₂f).toFinset, Complex.abs (z - ↑x) ^ (h₁f.order x).toNat ≠ 0 := by
2024-09-10 16:50:29 +02:00
intro s hs
simp at hs
simp
intro h₂s
rw [h₂s] at h₂z
tauto
exact this
-- ∏ x ∈ ⋯.toFinset, Complex.abs (z - ↑x) ^ (h'₁f.order x).toNat ≠ 0
2024-09-11 11:09:03 +02:00
have : ∀ x ∈ (finiteZeros h₁U h₂U h₁f h'₂f).toFinset, Complex.abs (z - ↑x) ^ (h₁f.order x).toNat ≠ 0 := by
2024-09-10 16:50:29 +02:00
intro s hs
simp at hs
simp
intro h₂s
rw [h₂s] at h₂z
tauto
rw [Finset.prod_ne_zero_iff]
exact this
2024-08-21 17:04:45 +02:00
-- Complex.abs (F z) ≠ 0
simp
exact h₂F z h₁z
2024-09-11 10:24:45 +02:00
have int_logAbs_f_eq_int_G : ∫ (x : ) in (0)..2 * π, log ‖f (circleMap 0 1 x)‖ = ∫ (x : ) in (0)..2 * π, G (circleMap 0 1 x) := by
2024-08-22 13:09:03 +02:00
2024-08-21 17:04:45 +02:00
rw [intervalIntegral.integral_congr_ae]
rw [MeasureTheory.ae_iff]
apply Set.Countable.measure_zero
simp
have t₀ : {a | a ∈ Ι 0 (2 * π) ∧ ¬log ‖f (circleMap 0 1 a)‖ = G (circleMap 0 1 a)}
⊆ (circleMap 0 1)⁻¹' (Metric.closedBall 0 1 ∩ f⁻¹' {0}) := by
intro a ha
simp at ha
simp
by_contra C
2024-09-10 16:50:29 +02:00
have : (circleMap 0 1 a) ∈ Metric.closedBall 0 1 :=
circleMap_mem_closedBall 0 (zero_le_one' ) a
2024-08-21 17:04:45 +02:00
exact ha.2 (decompose_f (circleMap 0 1 a) this C)
apply Set.Countable.mono t₀
apply Set.Countable.preimage_circleMap
apply Set.Finite.countable
2024-09-11 11:09:03 +02:00
let A := finiteZeros h₁U h₂U h₁f h'₂f
2024-08-21 17:04:45 +02:00
2024-09-10 16:50:29 +02:00
have : (Metric.closedBall 0 1 ∩ f ⁻¹' {0}) = (Metric.closedBall 0 1).restrict f ⁻¹' {0} := by
ext z
simp
tauto
rw [this]
exact Set.Finite.image Subtype.val A
2024-08-21 17:04:45 +02:00
exact Ne.symm (zero_ne_one' )
2024-09-10 16:50:29 +02:00
2024-09-11 10:24:45 +02:00
have decompose_int_G : ∫ (x : ) in (0)..2 * π, G (circleMap 0 1 x)
2024-09-11 09:07:49 +02:00
= (∫ (x : ) in (0)..2 * π, log (Complex.abs (F (circleMap 0 1 x))))
2024-09-11 11:09:03 +02:00
+ ∑ x ∈ (finiteZeros h₁U h₂U h₁f h'₂f).toFinset, (h₁f.order x).toNat * ∫ (x_1 : ) in (0)..2 * π, log (Complex.abs (circleMap 0 1 x_1 - ↑x)) := by
2024-08-21 17:04:45 +02:00
dsimp [G]
rw [intervalIntegral.integral_add]
rw [intervalIntegral.integral_finset_sum]
simp_rw [intervalIntegral.integral_const_mul]
2024-09-11 09:07:49 +02:00
-- ∀ i ∈ (finiteZeros h₁U h₂U h'₁f h'₂f).toFinset,
-- IntervalIntegrable (fun x => (h'₁f.order i).toNat *
-- log (Complex.abs (circleMap 0 1 x - ↑i))) MeasureTheory.volume 0 (2 * π)
2024-09-11 11:06:45 +02:00
intro i _
2024-08-21 17:04:45 +02:00
apply IntervalIntegrable.const_mul
2024-09-11 09:07:49 +02:00
--simp at this
2024-08-22 13:09:03 +02:00
by_cases h₂i : ‖i.1‖ = 1
-- case pos
exact int'₂ h₂i
-- case neg
2024-08-21 17:04:45 +02:00
apply Continuous.intervalIntegrable
apply continuous_iff_continuousAt.2
intro x
have : (fun x => log (Complex.abs (circleMap 0 1 x - ↑i))) = log ∘ Complex.abs ∘ (fun x ↦ circleMap 0 1 x - ↑i) :=
rfl
rw [this]
apply ContinuousAt.comp
apply Real.continuousAt_log
simp
by_contra ha'
2024-08-22 13:09:03 +02:00
conv at h₂i =>
arg 1
rw [← ha']
rw [Complex.norm_eq_abs]
rw [abs_circleMap_zero 1 x]
simp
tauto
2024-08-21 17:04:45 +02:00
apply ContinuousAt.comp
apply Complex.continuous_abs.continuousAt
fun_prop
2024-08-22 13:09:03 +02:00
-- IntervalIntegrable (fun x => log (Complex.abs (F (circleMap 0 1 x)))) MeasureTheory.volume 0 (2 * π)
apply Continuous.intervalIntegrable
apply continuous_iff_continuousAt.2
intro x
have : (fun x => log (Complex.abs (F (circleMap 0 1 x)))) = log ∘ Complex.abs ∘ F ∘ (fun x ↦ circleMap 0 1 x) :=
rfl
rw [this]
apply ContinuousAt.comp
apply Real.continuousAt_log
simp [h₂F]
2024-09-11 09:07:49 +02:00
-- ContinuousAt (⇑Complex.abs ∘ F ∘ fun x => circleMap 0 1 x) x
2024-08-22 13:09:03 +02:00
apply ContinuousAt.comp
apply Complex.continuous_abs.continuousAt
apply ContinuousAt.comp
apply DifferentiableAt.continuousAt (𝕜 := )
apply HolomorphicAt.differentiableAt
2024-09-11 09:07:49 +02:00
simp [h'₁F]
-- ContinuousAt (fun x => circleMap 0 1 x) x
2024-08-22 13:09:03 +02:00
apply Continuous.continuousAt
apply continuous_circleMap
2024-09-11 09:07:49 +02:00
2024-09-11 11:09:03 +02:00
have : (fun x => ∑ s ∈ (finiteZeros h₁U h₂U h₁f h'₂f).toFinset, (h₁f.order s).toNat * log (Complex.abs (circleMap 0 1 x - ↑s)))
= ∑ s ∈ (finiteZeros h₁U h₂U h₁f h'₂f).toFinset, (fun x => (h₁f.order s).toNat * log (Complex.abs (circleMap 0 1 x - ↑s))) := by
2024-08-22 13:09:03 +02:00
funext x
simp
rw [this]
apply IntervalIntegrable.sum
2024-09-11 11:06:45 +02:00
intro i _
2024-08-22 13:09:03 +02:00
apply IntervalIntegrable.const_mul
2024-09-11 09:07:49 +02:00
--have : i.1 ∈ Metric.closedBall (0 : ) 1 := i.2
--simp at this
2024-08-22 13:09:03 +02:00
by_cases h₂i : ‖i.1‖ = 1
-- case pos
exact int'₂ h₂i
-- case neg
2024-09-11 09:07:49 +02:00
--have : i.1 ∈ Metric.ball (0 : ) 1 := by sorry
2024-08-22 13:09:03 +02:00
apply Continuous.intervalIntegrable
apply continuous_iff_continuousAt.2
intro x
have : (fun x => log (Complex.abs (circleMap 0 1 x - ↑i))) = log ∘ Complex.abs ∘ (fun x ↦ circleMap 0 1 x - ↑i) :=
rfl
rw [this]
apply ContinuousAt.comp
apply Real.continuousAt_log
simp
2024-08-21 17:04:45 +02:00
2024-08-22 13:09:03 +02:00
by_contra ha'
conv at h₂i =>
arg 1
rw [← ha']
rw [Complex.norm_eq_abs]
rw [abs_circleMap_zero 1 x]
simp
tauto
apply ContinuousAt.comp
apply Complex.continuous_abs.continuousAt
fun_prop
2024-08-21 17:04:45 +02:00
2024-08-22 14:21:14 +02:00
have t₁ : (∫ (x : ) in (0)..2 * Real.pi, log ‖F (circleMap 0 1 x)‖) = 2 * Real.pi * log ‖F 0‖ := by
let logAbsF := fun w ↦ Real.log ‖F w‖
have t₀ : ∀ z ∈ Metric.closedBall 0 1, HarmonicAt logAbsF z := by
intro z hz
apply logabs_of_holomorphicAt_is_harmonic
2024-09-11 09:07:49 +02:00
apply h'₁F z hz
2024-08-22 14:21:14 +02:00
exact h₂F z hz
apply harmonic_meanValue₁ 1 Real.zero_lt_one t₀
2024-09-11 10:24:45 +02:00
simp_rw [← Complex.norm_eq_abs] at decompose_int_G
rw [t₁] at decompose_int_G
conv at decompose_int_G =>
right
right
arg 2
intro x
right
rw [int₃ x.2]
simp at decompose_int_G
rw [int_logAbs_f_eq_int_G]
rw [decompose_int_G]
rw [h₃F]
simp
have {l : } : π⁻¹ * 2⁻¹ * (2 * π * l) = l := by
calc π⁻¹ * 2⁻¹ * (2 * π * l)
_ = π⁻¹ * (2⁻¹ * 2) * π * l := by ring
_ = π⁻¹ * π * l := by ring
_ = (π⁻¹ * π) * l := by ring
_ = 1 * l := by
rw [inv_mul_cancel₀]
exact pi_ne_zero
_ = l := by simp
rw [this]
rw [log_mul]
rw [log_prod]
simp
2024-09-11 11:09:03 +02:00
rw [finsum_eq_sum_of_support_subset _ (s := (finiteZeros h₁U h₂U h₁f h'₂f).toFinset)]
2024-09-11 10:24:45 +02:00
simp
simp
2024-09-11 11:06:45 +02:00
intro x ⟨h₁x, _⟩
2024-09-11 10:24:45 +02:00
simp
dsimp [AnalyticOn.order] at h₁x
simp only [Function.mem_support, ne_eq, Nat.cast_eq_zero, not_or] at h₁x
2024-09-11 11:09:03 +02:00
exact AnalyticAt.supp_order_toNat (AnalyticOn.order.proof_1 h₁f x) h₁x
2024-09-11 10:24:45 +02:00
--
intro x hx
simp at hx
simp
intro h₁x
nth_rw 1 [← h₁x] at h₂f
tauto
2024-08-22 14:21:14 +02:00
2024-09-11 10:24:45 +02:00
--
rw [Finset.prod_ne_zero_iff]
intro x hx
simp at hx
simp
intro h₁x
nth_rw 1 [← h₁x] at h₂f
tauto
2024-08-21 17:04:45 +02:00
2024-09-11 10:24:45 +02:00
--
simp
apply h₂F
simp
2024-09-11 15:48:43 +02:00
lemma const_mul_circleMap_zero
{R θ : } :
circleMap 0 R θ = R * circleMap 0 1 θ := by
rw [circleMap_zero, circleMap_zero]
simp
theorem jensen
{R : }
(hR : 0 < R)
(f : )
(h₁f : AnalyticOn f (Metric.closedBall 0 R))
(h₂f : f 0 ≠ 0) :
log ‖f 0‖ = -∑ᶠ s, (h₁f.order s).toNat * log (R * ‖s.1‖⁻¹) + (2 * π)⁻¹ * ∫ (x : ) in (0)..(2 * π), log ‖f (circleMap 0 R x)‖ := by
2024-09-12 07:52:26 +02:00
let : ≃L[] :=
{
toFun := fun x ↦ R * x
map_add' := fun x y => DistribSMul.smul_add R x y
map_smul' := fun m x => mul_smul_comm m (↑R) x
invFun := fun x ↦ R⁻¹ * x
left_inv := by
intro x
simp
rw [← mul_assoc, mul_comm, inv_mul_cancel₀, mul_one]
simp
exact ne_of_gt hR
right_inv := by
intro x
simp
rw [← mul_assoc, mul_inv_cancel₀, one_mul]
simp
exact ne_of_gt hR
continuous_toFun := continuous_const_smul R
continuous_invFun := continuous_const_smul R⁻¹
}
2024-09-11 15:48:43 +02:00
2024-09-12 07:52:26 +02:00
let F := f ∘
2024-09-11 15:48:43 +02:00
have h₁F : AnalyticOn F (Metric.closedBall 0 1) := by
apply AnalyticOn.comp (t := Metric.closedBall 0 R)
exact h₁f
2024-09-12 07:52:26 +02:00
intro x _
apply .toContinuousLinearMap.analyticAt x
2024-09-11 15:48:43 +02:00
2024-09-12 07:52:26 +02:00
intro x hx
have : x = R * x := by rfl
rw [this]
simp
simp at hx
rw [abs_of_pos hR]
calc R * Complex.abs x
_ ≤ R * 1 := by exact (mul_le_mul_iff_of_pos_left hR).mpr hx
_ = R := by simp
have h₂F : F 0 ≠ 0 := by
dsimp [F]
have : 0 = R * 0 := by rfl
rw [this]
simpa
2024-09-11 15:48:43 +02:00
let A := jensen_case_R_eq_one F h₁F h₂F
2024-09-12 08:56:01 +02:00
2024-09-11 15:48:43 +02:00
dsimp [F] at A
2024-09-12 07:52:26 +02:00
have {x : } : x = R * x := by rfl
repeat
simp_rw [this] at A
simp at A
2024-09-11 15:48:43 +02:00
simp
rw [A]
simp_rw [← const_mul_circleMap_zero]
simp
let e : (Metric.closedBall (0 : ) 1) → (Metric.closedBall (0 : ) R) := by
intro ⟨x, hx⟩
have hy : R • x ∈ Metric.closedBall (0 : ) R := by
simp
simp at hx
have : R = |R| := by exact Eq.symm (abs_of_pos hR)
rw [← this]
norm_num
calc R * Complex.abs x
_ ≤ R * 1 := by exact (mul_le_mul_iff_of_pos_left hR).mpr hx
_ = R := by simp
exact ⟨R • x, hy⟩
let e' : (Metric.closedBall (0 : ) R) → (Metric.closedBall (0 : ) 1) := by
intro ⟨x, hx⟩
have hy : R⁻¹ • x ∈ Metric.closedBall (0 : ) 1 := by
simp
simp at hx
have : R = |R| := by exact Eq.symm (abs_of_pos hR)
rw [← this]
norm_num
calc R⁻¹ * Complex.abs x
_ ≤ R⁻¹ * R := by
apply mul_le_mul_of_nonneg_left hx
apply inv_nonneg.mpr
exact abs_eq_self.mp (id (Eq.symm this))
_ = 1 := by
apply inv_mul_cancel₀
exact Ne.symm (ne_of_lt hR)
exact ⟨R⁻¹ • x, hy⟩
apply finsum_eq_of_bijective e
2024-09-12 08:56:01 +02:00
2024-09-11 15:48:43 +02:00
apply Function.bijective_iff_has_inverse.mpr
use e'
constructor
· apply Function.leftInverse_iff_comp.mpr
funext x
dsimp only [e, e', id_eq, eq_mp_eq_cast, Function.comp_apply]
conv =>
left
arg 1
rw [← smul_assoc, smul_eq_mul]
rw [inv_mul_cancel₀ (Ne.symm (ne_of_lt hR))]
rw [one_smul]
· apply Function.rightInverse_iff_comp.mpr
funext x
dsimp only [e, e', id_eq, eq_mp_eq_cast, Function.comp_apply]
conv =>
left
arg 1
rw [← smul_assoc, smul_eq_mul]
rw [mul_inv_cancel₀ (Ne.symm (ne_of_lt hR))]
rw [one_smul]
intro x
simp
2024-09-12 08:56:01 +02:00
by_cases hx : x = (0 : )
rw [hx]
simp
rw [log_mul, log_mul, log_inv, log_inv]
have : R = |R| := by exact Eq.symm (abs_of_pos hR)
rw [← this]
simp
left
congr 1
2024-09-11 15:48:43 +02:00
2024-09-12 08:56:01 +02:00
dsimp [AnalyticOn.order]
rw [← AnalyticAt.order_comp_CLE ]
2024-09-11 15:48:43 +02:00
2024-09-12 08:56:01 +02:00
--
simpa
--
have : R = |R| := by exact Eq.symm (abs_of_pos hR)
rw [← this]
apply inv_ne_zero
exact Ne.symm (ne_of_lt hR)
--
exact Ne.symm (ne_of_lt hR)
--
simp
constructor
· assumption
· exact Ne.symm (ne_of_lt hR)