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import OAI.Analysis.IrrationalRotation.Model.CircleSamplingGraph
import OAI.Analysis.IrrationalRotation.Sampling.CircleSamplingLp
import OAI.Analysis.IrrationalRotation.Sampling.CircleCharacterDynamics
import OAI.Analysis.IrrationalRotation.Rotation.WeightedGraphMarginals
import Mathlib.MeasureTheory.Group.Arithmetic
import Mathlib.MeasureTheory.Function.L1Space.Integrable
import Mathlib.MeasureTheory.Function.LpSeminorm.TriangleInequality
namespace OAI
noncomputable section
open MeasureTheory MeasureTheory.Measure
open scoped BigOperators ENNReal
namespace Invariant233.CircleParameterData
theorem measurable_samplingDensity (p : CircleParameterData) (θ : ℝ) (j n : ℕ)
(endpoint : Bool) : Measurable (p.samplingDensity θ j n endpoint) := by
unfold samplingDensity
apply Finset.measurable_prod
intro i hi
exact (measurable_orientedKernel endpoint (p.m j)
(Int.fract ((n : ℝ) * p.alpha θ i))).comp (p.measurable_coordinate i)
theorem samplingDensity_nonneg (p : CircleParameterData) (θ : ℝ) (j n : ℕ)
(endpoint : Bool) (hm : 0 < p.m j) (x : Circle) :
0 ≤ p.samplingDensity θ j n endpoint x := by
exact Finset.prod_nonneg fun i _ => (orientedKernel_bounds endpoint hm _ _).1
theorem samplingTranslation_measurable (θ : ℝ) (n : ℕ) :
Measurable (samplingTranslation θ n) :=
(continuous_id.add continuous_const).measurable
theorem samplingTranslation_measurePreserving (θ : ℝ) (n : ℕ) :
MeasurePreserving (samplingTranslation θ n) circleMeasure circleMeasure := by
change MeasurePreserving (fun x : Circle => x + (((n : ℝ) * θ : ℝ) : Circle))
volume volume
exact measurePreserving_add_right volume (((n : ℝ) * θ : ℝ) : Circle)
theorem coordinate_sub_samplingTranslation (p : CircleParameterData) (θ : ℝ)
(i n : ℕ) (x : Circle) :
p.coordinate i (x - (((n : ℝ) * θ : ℝ) : Circle)) =
Int.fract (p.coordinate i x - (n : ℝ) * p.alpha θ i) := by
have h := CircleCharacterDynamics.character_orbit_representative
(p.q i : ℤ) (-(n : ℤ)) θ x
simpa only [coordinate, rep, alpha, neg_zsmul, natCast_zsmul,
← AddCircle.coe_nsmul, nsmul_eq_mul, Int.cast_neg, Int.cast_natCast,
neg_mul, sub_eq_add_neg] using h
theorem kernel_fract_first (m : ℕ) (z v : ℝ) :
kernel m (Int.fract z) v = kernel m z v := by
unfold kernel delta
rw [Int.fract_fract]
theorem fract_sub_fract_right (z v : ℝ) :
Int.fract (z - Int.fract v) = Int.fract (z - v) := by
have he : z - Int.fract v = z - v + (⌊v⌋ : ℤ) := by
rw [Int.fract]
ring
rw [he, Int.fract_add_intCast]
theorem samplingDensity_inverse_translation (p : CircleParameterData) (θ : ℝ)
(j n : ℕ) (x : Circle) :
p.samplingDensity θ j n false (x - (((n : ℝ) * θ : ℝ) : Circle)) =
p.samplingDensity θ j n true x := by
unfold samplingDensity
apply Finset.prod_congr rfl
intro i hi
rw [p.coordinate_sub_samplingTranslation]
simp only [orientedKernel, Bool.false_eq_true, ↓reduceIte, kernel_fract_first]
unfold kernel delta
rw [fract_sub_fract_right]
theorem samplingGraph_first_marginal (p : CircleParameterData) (θ : ℝ)
(j n : ℕ) :
(p.samplingGraph θ j n).map Prod.fst =
circleMeasure.withDensity
(fun x => ENNReal.ofReal (p.samplingDensity θ j n false x)) := by
exact WeightedGraphMarginals.map_fst_graph _ (samplingTranslation_measurable θ n)
theorem samplingGraph_second_marginal (p : CircleParameterData) (θ : ℝ)
(j n : ℕ) :
(p.samplingGraph θ j n).map Prod.snd =
circleMeasure.withDensity
(fun x => ENNReal.ofReal (p.samplingDensity θ j n true x)) := by
rw [samplingGraph, WeightedGraphMarginals.map_snd_graph _
(samplingTranslation_measurable θ n)]
rw [WeightedGraphMarginals.map_withDensity_inverse circleMeasure
(samplingTranslation_measurePreserving θ n)
(S := fun x => x - (((n : ℝ) * θ : ℝ) : Circle))
(continuous_id.sub continuous_const).measurable
(fun x => by simp [samplingTranslation])
(p.measurable_samplingDensity θ j n false).ennreal_ofReal]
congr 1
funext x
rw [p.samplingDensity_inverse_translation]
theorem samplingGraphAverage_first_marginal (p : CircleParameterData) (θ : ℝ)
(j r : ℕ) (hm : 0 < p.m j) :
(p.samplingGraphAverage θ j r).map Prod.fst =
circleMeasure.withDensity
(fun x => ENNReal.ofReal (p.samplingAverage θ j r false x)) := by
rw [samplingGraphAverage, Measure.map_smul _ measurable_fst.aemeasurable,
WeightedGraphMarginals.map_finset_sum _ _ measurable_fst]
simp_rw [p.samplingGraph_first_marginal]
exact (WeightedGraphMarginals.withDensity_real_finset_sum circleMeasure
(p.samples j r) (fun n => p.samplingDensity θ j n false)
(fun n _ => p.measurable_samplingDensity θ j n false)
(fun n _ x => p.samplingDensity_nonneg θ j n false hm x)
(by positivity : 0 ≤ 1 / ((p.samples j r).card : ℝ))).symm
theorem samplingGraphAverage_second_marginal (p : CircleParameterData) (θ : ℝ)
(j r : ℕ) (hm : 0 < p.m j) :
(p.samplingGraphAverage θ j r).map Prod.snd =
circleMeasure.withDensity
(fun x => ENNReal.ofReal (p.samplingAverage θ j r true x)) := by
rw [samplingGraphAverage, Measure.map_smul _ measurable_snd.aemeasurable,
WeightedGraphMarginals.map_finset_sum _ _ measurable_snd]
simp_rw [p.samplingGraph_second_marginal]
exact (WeightedGraphMarginals.withDensity_real_finset_sum circleMeasure
(p.samples j r) (fun n => p.samplingDensity θ j n true)
(fun n _ => p.measurable_samplingDensity θ j n true)
(fun n _ x => p.samplingDensity_nonneg θ j n true hm x)
(by positivity : 0 ≤ 1 / ((p.samples j r).card : ℝ))).symm
theorem samplingGraphAverage_finite (p : CircleParameterData) (θ : ℝ)
(j r : ℕ) (hm : 0 < p.m j) : IsFiniteMeasure (p.samplingGraphAverage θ j r) := by
let : IsFiniteMeasure circleMeasure := by unfold circleMeasure; infer_instance
have hi : Integrable (p.samplingAverage θ j r false) circleMeasure :=
(p.memLp_samplingAverage θ j r false hm 1).integrable le_rfl
have hn : 0 ≤ᵐ[circleMeasure] p.samplingAverage θ j r false :=
Filter.Eventually.of_forall fun x => (p.samplingAverage_bounds θ j r false hm x).1
have ht := (lintegral_ofReal_ne_top_iff_integrable
hi.aestronglyMeasurable hn).2 hi
have : IsFiniteMeasure ((p.samplingGraphAverage θ j r).map Prod.fst) := by
rw [p.samplingGraphAverage_first_marginal θ j r hm]
exact isFiniteMeasure_withDensity ht
exact Measure.isFiniteMeasure_of_map measurable_fst.aemeasurable
theorem samplingGraph_ae_graph (p : CircleParameterData) (θ : ℝ) (j n : ℕ) :
∀ᵐ xy ∂p.samplingGraph θ j n, xy.2 = samplingTranslation θ n xy.1 := by
unfold samplingGraph
have hg : Measurable (fun x => (x, samplingTranslation θ n x)) :=
measurable_id.prodMk (samplingTranslation_measurable θ n)
apply (ae_map_iff hg.aemeasurable ?_).2
· exact Filter.Eventually.of_forall fun _ => rfl
· exact (isClosed_eq continuous_snd
(continuous_fst.add continuous_const)).measurableSet
theorem samplingGraph_ae_positive_density (p : CircleParameterData) (θ : ℝ)
(j n : ℕ) :
∀ᵐ xy ∂p.samplingGraph θ j n, 0 < p.samplingDensity θ j n false xy.1 := by
unfold samplingGraph
have hg : Measurable (fun x => (x, samplingTranslation θ n x)) :=
measurable_id.prodMk (samplingTranslation_measurable θ n)
apply (ae_map_iff hg.aemeasurable
(measurableSet_lt measurable_const
((p.measurable_samplingDensity θ j n false).comp measurable_fst))).2
apply (ae_withDensity_iff (p.measurable_samplingDensity θ j n false).ennreal_ofReal).2
exact Filter.Eventually.of_forall fun x hx =>
ENNReal.ofReal_pos.mp (pos_iff_ne_zero.mpr hx)
theorem samplingGraphAverage_ae_graph (p : CircleParameterData) (θ : ℝ) (j r : ℕ) :
∀ᵐ xy ∂p.samplingGraphAverage θ j r,
∃ n ∈ p.samples j r, xy.2 = samplingTranslation θ n xy.1 := by
unfold samplingGraphAverage
apply ae_smul_measure
apply ae_finsetSum_measure_iff.mpr
intro n hn
filter_upwards [p.samplingGraph_ae_graph θ j n] with xy hxy
exact ⟨n, hn, hxy⟩
theorem samplingGraphAverage_ae_positive_density_graph (p : CircleParameterData)
(θ : ℝ) (j r : ℕ) :
∀ᵐ xy ∂p.samplingGraphAverage θ j r,
∃ n ∈ p.samples j r, 0 < p.samplingDensity θ j n false xy.1 ∧
xy.2 = samplingTranslation θ n xy.1 := by
unfold samplingGraphAverage
apply ae_smul_measure
apply ae_finsetSum_measure_iff.mpr
intro n hn
filter_upwards [p.samplingGraph_ae_graph θ j n,
p.samplingGraph_ae_positive_density θ j n] with xy hxy hpos
exact ⟨n, hn, hpos, hxy⟩
end Invariant233.CircleParameterData
namespace Invariant233.CircleParameterLaws
open CircleParameterData
theorem samplingAverage_eLpNorm_le_two {θ : ℝ} {p : CircleParameterData}
(hp : CircleParameterLaws θ p) (j : ℕ) (hj : 1 ≤ j) (r : ℕ)
(hr : r < p.q (p.blockEnd (j - 1))) (endpoint : Bool) :
eLpNorm (p.samplingAverage θ j r endpoint) 2 circleMeasure ≤ 2 := by
let : IsProbabilityMeasure circleMeasure := by
constructor
change volume (Set.univ : Set Circle) = 1
exact UnitAddCircle.measure_univ
have he := eLpNorm_add_le
(f := fun x => p.samplingAverage θ j r endpoint x - 1)
(g := fun _ : Circle => (1 : ℝ)) (μ := circleMeasure)
(by norm_num : (1 : ENNReal) ≤ 2)
have hfun : (fun x => p.samplingAverage θ j r endpoint x - 1) +
(fun _ : Circle => (1 : ℝ)) = p.samplingAverage θ j r endpoint := by
funext x
simp
rw [hfun] at he
have hc : eLpNorm (fun _ : Circle => (1 : ℝ)) 2 circleMeasure = 1 := by
rw [eLpNorm_const' _ (by norm_num) (by norm_num)]
simp
rw [hc] at he
have hjR : (1 : ℝ) ≤ j := by exact_mod_cast hj
have hfrac : ENNReal.ofReal (1 / (j : ℝ)) ≤ 1 := by
apply ENNReal.ofReal_le_one.mpr
simpa using one_div_le_one_div_of_le (by norm_num : (0 : ℝ) < 1) hjR
calc
_ ≤ eLpNorm (fun x => p.samplingAverage θ j r endpoint x - 1) 2 circleMeasure + 1 := he
_ ≤ ENNReal.ofReal (1 / (j : ℝ)) + 1 :=
add_le_add (hp.sampling_L2 j hj r hr endpoint).le le_rfl
_ ≤ (1 : ENNReal) + 1 := add_le_add hfrac le_rfl
_ = 2 := by norm_num
theorem samplingGraphAverage_ae_positive_graph {θ : ℝ} {p : CircleParameterData}
(hp : CircleParameterLaws θ p) (j : ℕ) (hj : 1 ≤ j) (r : ℕ)
(hr : r < p.q (p.blockEnd (j - 1))) :
∀ᵐ xy ∂p.samplingGraphAverage θ j r,
∃ n ∈ p.samples j r, 0 < n ∧ xy.2 = samplingTranslation θ n xy.1 := by
filter_upwards [p.samplingGraphAverage_ae_graph θ j r] with xy hxy
obtain ⟨n, hn, he⟩ := hxy
exact ⟨n, hn, hp.samples_positive j hj r hr n hn, he⟩
end Invariant233.CircleParameterLaws
end
end OAI