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LeanPool.Superdiffusion.Algsuperdiff.Section3.Provider.CoarseEllipticity.LambdaGridBridge

LambdaGridBridge #

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

The on-grid lambdaSq bridge: Lambda_{s,q} as a weighted grid series #

Provider/CoarseEllipticity/ScaleSummation.lean and Provider/CoarseEllipticity/LowerLeg.lean each retain the same conditional analytic input, an explicit binder called hgrid: the domination of the coarse-grained ellipticity constant by a weighted series of the per-scale triadic grid maxima. This module supplies the deterministic content of that binder and pins, with machine-checked negative controls, exactly which part of it can and cannot be transported to this repository's Section 3 observables.

The two seams, and what happens to each #

(i) The index/pole seam. ABK26 defines

Lambda_{s,q}(cu_m;a) = ( c_{sq} sum_{k<=m} 3^{-sq(m-k)}
                             max_{z in 3^k Zd cap cu_m} |b(z+cu_k;a)|^{q/2} )^{2/q}

and CoarseGraining's Ch02.LambdaSqFinite is literally this, with c_{sq} = Ch02.geometricDiscount s q = 1 - 3^{-sq} and gap index n = m - k. CoarseGraining's own bridge to a linear grid series exists only at q = 1 and delivers the pole s, whereas the consumers need the summation performed at the q/2-power level, before the outer 2/q root. That is what tsum_weighted_rpow_root_le does, by countable subadditivity of the concave power x |-> x^{2/q} at q >= 2; the resulting weight arithmetic is geometricWeight_rpow_succ:

(c_{sq} 3^{-sq(k+1)})^{2/q} = gridSumConst s q * gridWeight (2 s) k

so the pole is 2s for every q >= 2, not sq, and the collar absorption gridWeight_mul_rpow of GridWeights.lean then moves it to the printed (2s - gamma) (geometricWeight_rpow_succ_collar). This settles the weight-convention question flagged, and the "s-times-gridWeight (2s-gamma)" reading of the printed deterministic pole is recovered, not assumed, through gridSumConst_two_le (gridSumConst s 2 = 1 - 3^{-2s} <= 4 s). At the ruled exponent q = 2 the two exponents q/2 and 2/q are both 1, the subadditivity step is vacuous, and the bridge is an equality (LambdaSqFinite_two_eq_top_add_gridSum) needing no summability binder at all.

The gap-0 term is carried explicitly. gridWeight covers gaps >= 1 only (GridWeights.lean); the source series has a gap-0 summand, the one-cube quantity |b(cu_m;a)| at the top scale. Every statement below displays it as a separate summand gridSumConst s q * (top-scale maximum); nothing is silently dropped.

A.mk is Classical.choose of an existential and carries no pointwise information about the literal observable, so the bridge proved here held pathwise for the literal observables (cutoffUpperEllipticityLiteral_two_eq_top_add_gridSum and its lower twin; names corrected; the current conditional/A inventory describes the headline families) and only almost everywhere for the representatives (cutoffUpperEllipticity_ae_le_top_add_gridSum). The route suggested by the genuine centered-cube rfl between the two exported observables did not extend: that equality identified two representatives, not a representative with a literal, and two negative controls confirmed it (cutoffUpperEllipticity = cutoffUpperEllipticityLiteral was not a definitional equality; neither was cubeUpperEllipticity M Q L ... = cutoffUpperEllipticity M m L ... at an arbitrary cube Q).

How it was removed. Exactly that change was made. On the source range 0 < s the clamp is inert (Observable.cutoffLowerEllipticityInv_eq_literal, Observable.cutoffUpperEllipticity_eq_literal), so every pathwise statement of this module descends to the exported observables at every sample point. Both negative controls above are now vacuous: the first equality holds (not by rfl, but by max_eq_right at 0 < s), and the second holds whenever Q = originCube d m.

The a.e. shadows below remain true, remain the statements the current consumers are written against, and are now provable in one line from the pointwise forms.

The leg-by-leg consequence, restated.

Main results #

References #

1. The q/2-power level summation #

theorem Algsuperdiff.Section3.Provider.CoarseEllipticity.tsum_rpow_le_tsum_rpow {b : ℕ → ℝ} {theta : ℝ} (htheta0 : 0 < theta) (htheta1 : theta ≤ 1) (hb : ∀ (n : ℕ), 0 ≤ b n) (hsum : Summable b) (hsumtheta : Summable fun (n : ℕ) => b n ^ theta) :
(∑' (n : ℕ), b n) ^ theta ≤ ∑' (n : ℕ), b n ^ theta

Countable subadditivity of the concave power. For 0 < theta <= 1 and a nonnegative summable b whose theta-powers are also summable, (sum b)^theta <= sum b^theta.

This is the step the printed proof performs silently when it sums the per-scale displays inside the q/2-power and only then takes the 2/q root.

theorem Algsuperdiff.Section3.Provider.CoarseEllipticity.tsum_weighted_rpow_root_le {q : ℝ} {w f : ℕ → ℝ} (hq : 2 ≤ q) (hw : ∀ (n : ℕ), 0 ≤ w n) (hf : ∀ (n : ℕ), 0 ≤ f n) (hsum : Summable fun (n : ℕ) => w n * f n ^ (q / 2)) (hsumlin : Summable fun (n : ℕ) => w n ^ (2 / q) * f n) :
(∑' (n : ℕ), w n * f n ^ (q / 2)) ^ (2 / q) ≤ ∑' (n : ℕ), w n ^ (2 / q) * f n

The q/2-power level summation (seam (i)). The weighted ell^{q/2} aggregate that defines Lambda_{s,q} is dominated by the linear series with the reweighted coefficients w^{2/q}, for every q >= 2.

2. The weight arithmetic of the 2/q root #

The k-independent constant produced by the 2/q root of the source's normalizer: c_{sq}^{2/q} = (1 - 3^{-sq})^{2/q}.

Equations
Instances For

    The gap-0 weight, after the 2/q root, is the bare constant.

    The index/pole identity of seam (i). After the 2/q root the source's gap-(k+1) weight is the grid weight at pole 2s, uniformly in q. This is why the printed poles are (2s - gamma)-type and not (sq - gamma)-type.

    3. The pathwise bridge at CoarseGraining's deterministic carriers #

    lambda_{s,q}^{-1} unfolded: the negative root of the source's series is inverted to the positive root, at every coefficient family and with no positivity side condition.

    7. The bridge at the Section 3 observables #

    The Section 3 literal upper observable is the Chapter 4 ambient observable at the cutoff field. NeZero d is a Prop class, so the instance carried inside the observable's definition and the one supplied here are definitionally equal.

    The Section 3 literal lower observable is the inverse of the Chapter 4 ambient observable at the cutoff field.

    8. The pointwise-valid upgrade, and the upper leg's summation #

    theorem Algsuperdiff.Section3.Provider.CoarseEllipticity.exists_pointwise_of_ae_threeTermSplit {Omega : Type u_1} [MeasurableSpace Omega] {mu : MeasureTheory.Measure Omega} {X U1 Uexp : Omega → ℝ} {b A1 A2 sigma1 sigma2 : ℝ} (hXmeas : Measurable X) (hU1meas : Measurable U1) (hUexpmeas : Measurable Uexp) (h1 : HCPolySupport.IndependentSums.IsBigOWith mu (HCPolySupport.IndependentSums.gammaSigma sigma1) U1 A1) (hexp : HCPolySupport.IndependentSums.IsBigOWith mu (HCPolySupport.IndependentSums.gammaSigma sigma2) Uexp A2) (hae : ∀ᵐ (omega : Omega) ∂mu, X omega ≤ b + U1 omega + Uexp omega) :
    ∃ (Udet : Omega → ℝ) (U1' : Omega → ℝ) (Uexp' : Omega → ℝ), (∀ (omega : Omega), X omega ≤ Udet omega + U1' omega + Uexp' omega) ∧ (∀ (omega : Omega), Udet omega ≤ b) ∧ Measurable U1' ∧ Measurable Uexp' ∧ HCPolySupport.IndependentSums.IsBigOWith mu (HCPolySupport.IndependentSums.gammaSigma sigma1) U1' A1 ∧ HCPolySupport.IndependentSums.IsBigOWith mu (HCPolySupport.IndependentSums.gammaSigma sigma2) Uexp' A2

    The pointwise-valid null-set upgrade. An almost-everywhere three-term domination with a deterministic first slot upgrades to a domination valid at every sample point, by moving the defect into the ordinary lane on a measurable null set.

    Nothing produced here is an almost-everywhere witness: U1' is an everywhere-defined measurable function, the domination is forall omega, and the Gamma tail is unchanged because IsBigOWith only sees the almost-everywhere class (Provider.Tail.isBigOWith_of_ae_eq). This upgrade is available to the upper leg only; the lower leg's single witness must majorize a whole L-indexed family at once, and on the null set that supremum is not known to be finite (see the module docstring).