On complemented subspaces of L1[0,1]L_1[0,1]

PL1/IntrinsicSpikes.lean

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1import PL1.IntrinsicSpikeEstimates2import PL1.ConcreteResolvents34/-!5# The dyadic intrinsic spike norm and separation bounds67This file sums the actual resolvent commutator estimates with the intrinsic8coordinate weights. The remaining inputs explicitly concern multiplication9and head/tail independence in the genuine Haar L¹ space, over real or complex10scalars. No alternative intrinsic norm is introduced.11-/1213noncomputable section14open MeasureTheory15open scoped BigOperators ENNReal NNReal1617namespace PL1.IntrinsicSpikes18open Noise Walsh IntrinsicGraph ResolventEstimates IntrinsicSpikeEstimates1920/-- The exact error coefficient in the manuscript's spike norm estimate. -/21def eta (T : PositiveTime) : ℝ := (2 / (T : ℝ)) * (dyadicRatio / (1 - dyadicRatio))2223theorem eta_pos (T : PositiveTime) : 0 < eta T :=24  mul_pos (div_pos (by norm_num) T.property)25    (div_pos dyadicRatio_pos one_sub_dyadicRatio_pos)2627theorem eta_eq (T : PositiveTime) : eta T = 2 / ((T : ℝ) * (Real.sqrt 2 - 1)) := by28  have hs : Real.sqrt 2 ≠ 0 := (Real.sqrt_pos.mpr (by norm_num)).ne'29  have hs1 : Real.sqrt 2 - 1 ≠ 0 := by30    have hsq := Real.sq_sqrt (by norm_num : (0 : ℝ) ≤ 2)31    have hnonneg := Real.sqrt_nonneg (2 : ℝ)32    nlinarith33  unfold eta dyadicRatio34  field_simp3536theorem exists_eta_lt {ε : ℝ} (hε : 0 < ε) : ∃ T : PositiveTime, eta T < ε := by37  let C : ℝ := 2 * (dyadicRatio / (1 - dyadicRatio))38  have hC : 0 < C := mul_pos (by norm_num)39    (div_pos dyadicRatio_pos one_sub_dyadicRatio_pos)40  let T : PositiveTime := ⟨C / ε + 1, by positivity⟩41  refine ⟨T, ?_⟩42  have heq : eta T = C / (T : ℝ) := by dsimp [eta, C]; ring43  rw [heq, div_lt_iff₀ T.property]44  have hc := div_mul_cancel₀ C hε.ne'45  change C < ε * (C / ε + 1)46  nlinarith4748def error (T : PositiveTime) (b : ℝ) : ℕ → ℝ49  | 0 => 050  | n + 1 => (2 / (T : ℝ)) * dyadicRatio ^ (n + 1) * b5152theorem error_summable (T : PositiveTime) (b : ℝ) : Summable (error T b) :=53  (summable_nat_add_iff 1).mp54    ((geometric_tail_summable.mul_left (2 / (T : ℝ))).mul_right b)5556theorem error_tsum (T : PositiveTime) (b : ℝ) : (∑' n, error T b n) = eta T * b := by57  rw [(error_summable T b).tsum_eq_zero_add]58  simp only [error, zero_add, tsum_mul_right, tsum_mul_left, geometric_tail_tsum, eta]5960variable {𝕜 : Type*} [RCLike 𝕜]6162theorem coordinate_commutator_le (rates : ℕ → ℝ≥0)63    (M : Lp 𝕜 1 haar →L[𝕜] Lp 𝕜 1 haar)64    (f : (dyadicSystem 𝕜 rates).IntrinsicSpace) (T : PositiveTime)65    (hdefect : ∀ t : PositiveTime,66      ‖(M (evalZero (dyadicSystem 𝕜 rates).analysis f) -67          resolventL1 𝕜 rates t (M (evalZero (dyadicSystem 𝕜 rates).analysis f))) -68        M (evalZero (dyadicSystem 𝕜 rates).analysis f -69          resolventL1 𝕜 rates t (evalZero (dyadicSystem 𝕜 rates).analysis f))‖ ≤70        2 * (t : ℝ) / (T : ℝ) * ‖evalZero (dyadicSystem 𝕜 rates).analysis f‖) :71    ∀ n, ‖(dyadicSystem 𝕜 rates).analysis n72          (M (evalZero (dyadicSystem 𝕜 rates).analysis f)) -73        M (coord (dyadicSystem 𝕜 rates).analysis n f)‖ ≤74      error T ‖evalZero (dyadicSystem 𝕜 rates).analysis f‖ n := by75  intro n76  rw [coord_eq]77  cases n with78  | zero => simp [DyadicSystem.analysis, analysisCoordinate, error]79  | succ n =>80    simp only [DyadicSystem.analysis, analysisCoordinate,81      smul_apply, sub_apply,82      ContinuousLinearMap.id_apply, map_smul, ← smul_sub, norm_smul,83      RCLike.norm_ofReal,84      abs_of_nonneg (inv_nonneg.mpr (pow_nonneg dyadicRatio_nonneg _))]85    have h := mul_le_mul_of_nonneg_left (hdefect (dyadicTime (n + 1)))86      (inv_nonneg.mpr (pow_nonneg dyadicRatio_nonneg (n + 1)))87    apply h.trans_eq88    have ht : (dyadicTime (n + 1) : ℝ) = (dyadicRatio ^ (n + 1)) ^ 2 := by89      dsimp [dyadicTime]90      rw [← pow_mul, ← pow_mul, Nat.mul_comm]91    rw [ht]92    dsimp [error]93    field_simp9495theorem exists_product (rates : ℕ → ℝ≥0)96    (M : Lp 𝕜 1 haar →L[𝕜] Lp 𝕜 1 haar)97    (f : (dyadicSystem 𝕜 rates).IntrinsicSpace) (T : PositiveTime)98    (hpres : ∀ n, ‖M (coord (dyadicSystem 𝕜 rates).analysis n f)‖ =99      ‖coord (dyadicSystem 𝕜 rates).analysis n f‖)100    (hcomm : ∀ n, ‖(dyadicSystem 𝕜 rates).analysis n101          (M (evalZero (dyadicSystem 𝕜 rates).analysis f)) -102        M (coord (dyadicSystem 𝕜 rates).analysis n f)‖ ≤103      error T ‖evalZero (dyadicSystem 𝕜 rates).analysis f‖ n) :104    ∃ g : (dyadicSystem 𝕜 rates).IntrinsicSpace,105      evalZero (dyadicSystem 𝕜 rates).analysis g =106        M (evalZero (dyadicSystem 𝕜 rates).analysis f) ∧107      |‖g‖ - ‖f‖| ≤ eta T * ‖evalZero (dyadicSystem 𝕜 rates).analysis f‖ := by108  simpa only [error_tsum] using IntrinsicSpikeEstimates.exists_product rfl M f109    (error T ‖evalZero (dyadicSystem 𝕜 rates).analysis f‖)110    (error_summable T _) hpres hcomm111112theorem separation (rates : ℕ → ℝ≥0)113    (M : Lp 𝕜 1 haar →L[𝕜] Lp 𝕜 1 haar)114    (h f g : (dyadicSystem 𝕜 rates).IntrinsicSpace)115    (hg : evalZero (dyadicSystem 𝕜 rates).analysis g =116      M (evalZero (dyadicSystem 𝕜 rates).analysis f)) (T : PositiveTime) (δ : ℝ)117    (hsep : ∀ n, (1 - 2 * δ) *118        (‖coord (dyadicSystem 𝕜 rates).analysis n h‖ +119          ‖coord (dyadicSystem 𝕜 rates).analysis n f‖) ≤120      ‖coord (dyadicSystem 𝕜 rates).analysis n h +121        M (coord (dyadicSystem 𝕜 rates).analysis n f)‖)122    (hcomm : ∀ n, ‖(dyadicSystem 𝕜 rates).analysis n123          (M (evalZero (dyadicSystem 𝕜 rates).analysis f)) -124        M (coord (dyadicSystem 𝕜 rates).analysis n f)‖ ≤125      error T ‖evalZero (dyadicSystem 𝕜 rates).analysis f‖ n) :126    (1 - 2 * δ) * (‖h‖ + ‖f‖) -127      eta T * ‖evalZero (dyadicSystem 𝕜 rates).analysis f‖ ≤ ‖h + g‖ := by128  simpa only [error_tsum] using IntrinsicSpikeEstimates.separation M h f g hg129    (error T ‖evalZero (dyadicSystem 𝕜 rates).analysis f‖)130    (error_summable T _) (1 - 2 * δ) hsep hcomm131132end PL1.IntrinsicSpikes133