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LeanPool.Superdiffusion.Algsuperdiff.Section3.Provider.MultiscaleEstimate.WaveSizesZeroth

WaveSizesZeroth #

Ported from scottnarmstrong/Superdiffusion at 7f20476385d4af418f110303085ad0740c9eba46. Module imports, support namespace and local option directives adapted for Lean Pool.

Provider: the zeroth-order leg and the full W^{2,∞} carrier of e.wave.sizes #

Companion of Provider/MultiscaleEstimate/WaveSizes.lean, which carries the derivative half of ABK26's wave-size display e.wave.sizes. This module adds the missing zeroth-order L∞ leg, forms the extended carrier, records the zeroth-order fidelity statement, and states the headline endpoint wave_sizes_bound at that extended carrier.

This is a provider endpoint only. It is not a source node, not a frozen declaration, and it does not close p.multiscale.estimate.

Why the zeroth order is required #

The printed display carries ‖k_m - k_{l-h}‖_{W^{2,∞}(z+cu_l)}. At p = ∞ the printed object is a maximum, not a sum. Reading at p = ∞ on a cube of side 3^l (where |U|^{-1/d} = 3^{-l}) and iterating to second order gives

3^{2l} ‖f‖_{W^{2,∞}(z+cu_l)} = max{‖f‖_{L∞(z+cu_l)}, 3^l ‖∇f‖_{L∞(z+cu_l)}, 3^{2l} ‖∇²f‖_{L∞(z+cu_l)}},

the p → ∞ limit of the printed ℓ^p combination. This module works with the three-order sum

‖f‖_{L∞(z+cu_l)} + 3^l ‖∇f‖_{L∞(z+cu_l)} + 3^{2l} ‖∇²f‖_{L∞(z+cu_l)},

which dominates that maximum, all three legs being nonnegative (and is at most three times it, so the two are equivalent). Every bound proved here against the sum is therefore a bound on the printed maximum: the domination runs in the safe direction and nothing is over-claimed. An earlier version of this docstring wrote the two with an =; that equation was false as written and is withdrawn. "The three-order object" below always means the sum.

The zeroth-order term is load-bearing. The frozen sensitivity remainder of Frozen/Section24/ResponseJSensitivity.lean carries vecNormSq p * h.w1Infinity ^ 2 with w1Infinity = max{‖∇h‖_{L∞(□₀)}, ‖h‖_{L∞(□₀)}} (Frozen/Section24/UnitCubeSkewW2Infinity/W1Infinity.lean), i.e. it contains ‖h‖_{L∞}, at a strictly positive coefficient; it is consumed verbatim at Provider/BadEvents/GoodLocalEvents.lean. The printed e.J.sensitivity.apppp merges that remainder with the gradientW1Infinity remainder into the single 3^{4l}‖·‖²_{W^{2,∞}} object. Any wave carrier that drops the L∞ term therefore does not feed the consumer. See the full discussion in the sibling module's docstring.

The extended carrier #

waveGaugeW2 m h R is the sum of the two legs at the triadic cube R of scale l = R.scale, read at the base point z = cubeCenter R:

waveGaugeW2 m h R = cubeSupBound R (l-h) m + waveGauge l m h (cubeCenter R).

The Γ₂ input for the zeroth-order leg is Stream.isBigOWith_gammaSigma_cubeSupBound (Provider/Stream/WaveTranslation.lean), the Γ₂ form whose only binder is hnm : n < m -- it carries no m ≤ Q.scale binder, which is what makes it usable at n = l-h, Q.scale = l ≤ m. The squared companions in that module do carry m ≤ Q.scale and are unusable in the wave lane; they are not touched here. cubeSupBound R m m = 0 covers the single degenerate case h = 0, l = m.

cubeCenter R = triadicCubeShift R holds by definitional unfolding, so the two legs really live on the same set: the cube R is exactly cubeCenter R + cu_l (openCubeSet_eq_translateSet_originCube_of_triadicCube).

The endpoint arithmetic, and why it is exactly s^{-2} #

At n = l-h, Q.scale = l = m-j the amplitude of isBigOWith_gammaSigma_cubeSupBound is

(3 max{1, log |subcubeShifts d (l-h) l|})^{1/2} · C_∞(d) · min{√(γ^{-1}), √(m-l+h)} · 3^{γm},

with |subcubeShifts d (l-h) l| = (2·3^{h+1}+1)^d, so the covering penalty is O(√(h+1)). After the 3^{-γl} normalization of waveSizeW2 the factor 3^{γm} leaves 3^{γj}, and after squaring and paying the grid maximum (waveGridConst d (1+j)) the per-scale base is

∝ (1+j) (j+h) 3^{2γj},

which is quadratic in the depth j. The exponent split three_rpow_split (legitimate because s ≥ 8γ) turns 3^{-sj} 3^{2γj} into 3^{-(3/4)sj}, and

s Σ_j (1+j)(j+h) 3^{-(3/4)sj} ≤ C h s^{-2},

the printed s^{-2} exactly. This is the reason the printed amplitude is s^{-2} and not the s^{-1} the derivative half alone would give: the zeroth-order leg, not the derivative leg, is what saturates the printed exponent. The summation lemma is tsum_weighted_sq_le below, proved from half_le_one_sub_three_rpow_neg and the elementary (1+j) x^j ≤ (1-x)^{-1} at the two auxiliary ratios 3^{-s/8} and 3^{-s/2}.

Main definitions #

Main results #

The fidelity convention, stated #

This module is stated against the honest scale-l convention for the volume-normalized norm on a cube of side 3^l. At p = ∞ that norm is the maximum

3^{2l}‖f‖_{W^{2,∞}(Q)} = max{‖f‖_{L∞(Q)}, 3^l‖∇f‖_{L∞(Q)}, 3^{2l}‖∇²f‖_{L∞(Q)}},

which is the reading (‖·‖_{W^{1,p}} with the |U|^{-p/d} weight on the zeroth-order term, taken at p = ∞ and iterated to second order) used throughout the Section 3 stream chain. The carrier is built against the three-order sum

‖f‖_{L∞(Q)} + 3^l‖∇f‖_{L∞(Q)} + 3^{2l}‖∇²f‖_{L∞(Q)},

which dominates that maximum (all three legs are nonnegative), so every bound proved here against the sum implies the corresponding bound on the printed W^{2,∞} object and claims nothing beyond it. Writing the sum with an = -- as an earlier version of this section did -- was wrong, and is withdrawn: the relation is max ≤ sum ≤ 3 max, and only the first inequality is used. What is available, and used, is that the zeroth-order leg is stated in the genuine L∞-norm carrier Stream.streamIncrementLinftyNorm, which Provider/Stream/IncrementLinftyNorm.lean identifies with eLpNorm ∞ (volume.restrict (openCubeSet (originCube d l))) -- the same shape as the frozen norms, one rescaling away.

The grid/lattice identification, asserted not proved #

Unchanged from the sibling module: the printed index set z ∈ 3^l Z^d ∩ cu_m is realized as descendantsAtScale (originCube d m) l with z:= cubeCenter R. This is the convention inherited from Localization.legScaleAverage (Provider/Localization/Breakdown.lean), asserted and not proved; the required set-equality pair is recorded verbatim in the sibling module's docstring. No declaration here depends on it being a bijection.

References #

Elementary real arithmetic: the quadratic base #

All of this section is abstract-real: no model, no measure, no cube.

theorem Algsuperdiff.Section3.Provider.MultiscaleEstimate.summable_weighted_sq {s gamma K : ℝ} (hs : 0 < s) (hs1 : s ≤ 1) (hsg : 8 * gamma ≤ s) (hK : 0 ≤ K) :
Summable fun (j : ℕ) => 3 ^ (-s * ↑j) * (3 ^ (2 * gamma * ↑j) * ((1 + ↑j) ^ 2 * K))

The quadratic-base weighted scale family is summable.

theorem Algsuperdiff.Section3.Provider.MultiscaleEstimate.tsum_weighted_sq_le {s gamma K : ℝ} (hs : 0 < s) (hs1 : s ≤ 1) (hsg : 8 * gamma ≤ s) (hK : 0 ≤ K) :
∑' (j : ℕ), 3 ^ (-s * ↑j) * (3 ^ (2 * gamma * ↑j) * ((1 + ↑j) ^ 2 * K)) ≤ 1024 * K / s ^ 3

The quadratic-base weighted scale sum, at s^{-3}.

The covering penalty of the zeroth-order leg #

The dimensional constant of the covering penalty of e.km.kn.Linfty at the wave lane's cutoff depth.

Duplication, disclosed. This constant and the lemma cover_log_le below re-derive a proved result of the same family, by the same route, from inside this module's own import closure: Provider/Stream/LargeCubeLinfty.lean bounds the same 3 max{1, log |subcubeShifts d n l|} in three_mul_max_one_log_card_subcubeShifts_le, at the constant largeCubeLogConst = 3(1 + 3 log 3) there, by the same three steps. The constants are different (3(1 + 2d log 3) here, with d inside; d sits outside there as a separate factor), and the reason for re-deriving rather than consuming is the h = 0 case -- see cover_log_le.

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    The zeroth-order leg #

    The Γ₂ amplitude of the zeroth-order leg at depth j = m - l and cutoff h, after the 3^{-γl} normalization: the covering penalty √(C(d)(1+h)), the e.km.kn.Linfty constant, the layer count √(j+h), and the residual 3^{γ j} left over from 3^{γ m} = 3^{γ j} 3^{γ l}.

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      The Γ₂ estimate of the zeroth-order leg. On the triadic cube R of scale l = m - j, the uniform supremum gauge of k_m - k_{l-h} obeys

      cubeSupBound R (l-h) m ≤ O_{Γ₂}(waveSupAmp M h j · 3^{γ l}),

      the amplitude being the e.km.kn.Linfty amplitude of Stream.isBigOWith_gammaSigma_cubeSupBound with the covering penalty made explicit. Unlike the derivative leg, this amplitude does grow with the scale gap j = m - l, through √(j+h) and 3^{γ j}; that growth is exactly what makes the l-sum land at the printed s^{-2}.

      The extended carrier #

      The extended wave carrier. The full three-order object of the printed display at the cube R of scale l = R.scale, read at the base point z = cubeCenter R:

      waveGaugeW2 m h R = ‖k_m-k_{l-h}‖_{L∞(R)}-gauge + waveGauge l m h z,

      the first summand the proved uniform supremum gauge Stream.cubeSupBound and the second the derivative half of the sibling module. It dominates 3^{2l}‖k_m-k_{l-h}‖_{W^{2,∞}(z+cu_l)}; the zeroth-order half of that domination is streamIncrementLinftyNorm_le_waveGaugeW2.

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        The zeroth-order half of the fidelity statement. The literal L∞ norm of the realized increment k_m - k_{l-h} on the cube R, in the genuine L∞-norm carrier Stream.streamIncrementLinftyNorm read at the translated sample (equivalently: on cubeCenter R + cu_l, which is R), is dominated by the extended carrier.

        The per-cube Γ₂ amplitude of the extended carrier: the countable-triangle constant applied to the two legs.

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          The per-cube Γ₂ estimate at the extended carrier. On every triadic cube R of scale l = m - j,

          3^{2l}‖k_m-k_{l-h}‖_{W^{2,∞}(z+cu_l)} ≤ O_{Γ₂}(waveAmpW2 M h j · 3^{γ l}).

          The per-cube quantity, the grid maximum, and the scale sum #

          The printed per-cube quantity of e.wave.sizes at the extended carrier, 3^{(2-γ)l}‖k_m-k_{l-h}‖_{W^{2,∞}(z+cu_l)}: the scale-l normalized carrier already carries 3^{2l}, so what is left is 3^{-γl}.

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            The per-cube Γ₂ estimate at the printed normalization.

            The grid maximum of the printed per-cube quantity at depth j = m - l, at the extended carrier.

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              The per-scale Γ₁ amplitude at the extended carrier: the per-cube amplitude squared, times the grid-maximum penalty.

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                The per-scale Γ₁ estimate at the extended carrier.

                noncomputable def Algsuperdiff.Section3.Provider.MultiscaleEstimate.waveSizesTotalW2 {d : ℕ} (M : ABKModel d) (m : ℤ) (h : ℕ) (s : ℝ) (omega : Cutoff.ShellSeq d) :

                The left-hand side of e.wave.sizes at the extended carrier, reindexed by the depth j = m - l.

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                  The per-scale power mean is at most the squared grid maximum. As in the sibling module, d ≠ 0 is derived from M, not assumed.

                  Measurability hook, per-scale level, extended carrier.

                  The cutoff-dependent per-scale majorant of the extended carrier: the constant K for which the per-scale Γ₁ amplitude is at most (1+j)^2 3^{2γj} K.

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                    theorem Algsuperdiff.Section3.Provider.MultiscaleEstimate.waveLayerAmpW2_le {d : ℕ} (M : ABKModel d) (h j : ℕ) :
                    waveLayerAmpW2 M h j ≤ 3 ^ (2 * M.gamma * ↑j) * ((1 + ↑j) ^ 2 * waveKW2 d h)

                    The per-scale amplitude is dominated by the quadratic base.

                    e.wave.sizes at the extended carrier and the printed s^{-2}. For every integer cutoff h and every s ∈ [8γ, 1],

                    s Σ_{l ≤ m} 3^{-s(m-l)} (⨍_z (3^{(2-γ)l}‖k_m-k_{l-h}‖_{W^{2,∞}(z+cu_l)})^{2d/s})^{s/d} ≤ O_{Γ₁}(C(d,h) s^{-2}),

                    with the full W^{2,∞} object on the left. The exponent is exactly the printed one: the zeroth-order leg's quadratic base is what saturates it.

                    The printed cutoff h = ⌈C|log ε|⌉ #

                    The integer cutoff. The manuscript sets h := C|log ε|, which is not an integer, while every occurrence of k_{l-h} needs an integer scale. This is the ceiling; the overshoot is a fixed factor, absorbed into the dimensional constant below.

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                      theorem Algsuperdiff.Section3.Provider.MultiscaleEstimate.wave_sizes_bound (d : ℕ) {C0 : ℝ} (hC0 : 0 < C0) :
                      ∃ (C : ℝ), 0 < C ∧ ∀ (M : ABKModel d) (m : ℤ) (eps s : ℝ), 0 < eps → eps ≤ 1 → 0 < s → s ≤ 1 → 8 * M.gamma ≤ s → HCPolySupport.IndependentSums.IsBigOWith (↑M.P) (HCPolySupport.IndependentSums.gammaSigma 1) (fun (omega : Cutoff.ShellSeq d) => waveSizesTotalW2 M m (waveCutoff C0 eps) s omega) (C * eps ^ (-C) / s ^ 2)

                      e.wave.sizes in the printed form, at the extended W^{2,∞} carrier. For every cutoff coefficient C₀ > 0 there is a constant C, depending only on the dimension and C₀, with

                      s Σ_{l ≤ m} 3^{-s(m-l)} (⨍_{z ∈ 3^l Z^d ∩ cu_m} (3^{(2-γ)l}‖k_m-k_{l-h}‖_{W^{2,∞}(z+cu_l)})^{2d/s})^{s/d} ≤ O_{Γ₁}(C s^{-2} ε^{-C})

                      at the integer cutoff h = ⌈C₀|log ε|⌉, for every ε ∈ (0,1] and every s ∈ [8γ, 1]. The left-hand side carries the full three-order object, not merely its derivative half.