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LeanPool.Superdiffusion.Algsuperdiff.Section4.Provider.Homogenization.HomSpineCzGridDepthTest

HomSpineCzGridDepthTest #

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

The SINGLE-DEPTH dual test: the exact pairing and the FREE flat part #

What this file is for #

HomSpineCzGridDualTest builds the MULTI-depth aggregate G₀ = Σ_{j≤N} g_j and proves its pairing exact. The multi-depth flat part then costs a Hölder-in-depth factor (1-3^{-s·p})^{-1/p}, which the necessity record of HomSpineCzGridGaugeRefuted shows SHARP. This file does the SINGLE depth, where that factor is not merely avoidable but absent by an exact computation:

  ⟨F, g_j⟩              =  cubeEuclideanNegativeBesovDepthEnergy Q s p F j   (EXACT)
  3^{-s·m}‖g_j‖_{L^{p'}}  =  3^{-s·j} · (depth energy)^{1/p'}                  (EXACT)

so the flat half of the single-depth full norm is bounded by (depth energy)^{1/p'} at CONSTANT ONE, with room 3^{-s·j} to spare — no geometric factor, no band, no s₀. Both displays are proved below (§1, §3).

The residue, measured exactly — and a WARNING #

What is NOT free at a single depth is the Gagliardo half. §4 records the exact band arithmetic. Writing ℓ = 3^{m-j} for the depth-j cell side and banding the double integral at |x-y| ~ 3^{m-k}:

So the single-depth Gagliardo bound carries a factor (1 + min(j·log 3 + c_d, (s·p')^{-1}))^{1/p'}, NOT C(d,p). The factor is real, not an artefact of the estimate: the alternating field ((F)_R = ±e_1 on the depth-j cells) makes |g_j(x) - g_j(y)| of full size for a fixed fraction of the far pairs. At the Step-3 pin s ≈ |log γ|⁻¹ this is |log γ|^{1/p'} — WORSE than the banded lane's |log γ|^{1/p} (p' ≈ 1, p = 4d).

What this file proves #

1. The pairing at ONE depth #

The depth-j slice of HomSpineCzGridDualTest's grid dual test pairs with F against exactly the depth-j term of CoarseGraining's running-scale negative Besov seminorm. No sum over depths is taken, so no Hölder in the depth index is spent and no geometric factor appears.

The real-valued single-depth pairing: the cube average of ⟨F, g_j⟩ is 3^{s·p·(m-j)} times the depth-j descendant average of ‖(F)_R‖^p.

The single-depth pairing is nonnegative: it is a geometric weight times a descendant average of p-th powers.

THE SINGLE-DEPTH EXACT PAIRING.

  ⟨F, g_j⟩ = cubeEuclideanNegativeBesovDepthEnergy Q s p F j

on the nose — the depth-j gauge term, with no constant spent, no √d, and no inequality. This is the whole of HomSpineCzGridDualTest's exact-duality mechanism read at ONE depth: the depth-j cells partition Q, the slice is constant on each, and vecSupDual realizes the sup-norm duality exactly.

2. The flat part at ONE depth: the cell-measure bookkeeping #

One depth, one geometric weight, no Hölder in the depth index. The depth-j cells carry normalized measure |D_j|⁻¹ each, so the normalized L^{p'} norm of the slice is the ℓ^{p'} average of the cell values, and the identity (p-1)·p' = p turns it into the depth energy to the power 1/p'.

The r-th power of the pointwise Euclidean size of a depth slice, as a sum of indicators of the depth-j cells.

The Euclidean size of a dual-test coefficient: the vecSupDual factor is a Euclidean unit vector, so no constant is spent.

3. The flat half of the single-depth full norm, at CONSTANT ONE #

The identity behind the display is (p-1)·p' = p together with p·p' = p + p': the depth-j slice has normalized L^{p'} mass 3^{s·p·(m-j)}·A_j^{1/p'} with A_j the descendant average of ‖(F)_R‖^p, and the scale weight 3^{-s·m·p'} turns the product into 3^{-s·j·p'} times the depth energy 3^{s·p·(m-j)}·A_j. The spare factor 3^{-s·j·p'} ≤ 1 is thrown away below.

THE SINGLE-DEPTH FLAT HALF IS FREE.

  3^{-s·m·p'} · ‖g_j‖_{L^{p'}(Q)}^{p'}  ≤  cubeEuclideanNegativeBesovDepthEnergy Q s p F j

at constant ONE, uniformly in s, j, Q, F — no band, no s₀, no (1-3^{-s·p})^{-1/p}. (The true value of the left side is 3^{-s·j·p'} times the right side; the spare factor is discarded.) This is the display the multi-depth aggregate cannot have: there the same computation is followed by a Minkowski sum and a discrete Hölder over the depths, and THAT is what buys the geometric factor the necessity record of HomSpineCzGridGaugeRefuted shows sharp.

4. The band arithmetic of the Gagliardo half: near bands uniform, far bands NOT #

A depth-j piecewise constant differs only across the depth-j skeleton, so the Gagliardo double integral splits at the cell side ℓ = 3^{m-j}.

The near-band geometric constant (1-3^{-1/2})^{-1}: the whole k ≥ j half of the banded boundary-layer estimate, at any admissible s·p' ≤ 1/2.

Equations
Instances For

    The near half is uniform. On the band s·p' ≤ 1/2 the near bands sum at ratio at most 3^{-1/2}, so the whole near half costs nearBandGeometricConstant — no s, no j, no γ.

    THE SINGLE-DEPTH GAUGE INEQUALITY.

      (depth energy)^{1/p}  ≤  (1+Cg^{p'})^{1/p'} · ‖F‖_{W^{-s,p}(Q), smooth dual}
    

    from the Gagliardo input alone: the exact pairing of §1, the free flat half of §3, CoarseGraining's pairing bound, and a cancellation of the common factor (depth energy)^{1/p'} — legitimate because the depth energy is an ENNReal.ofReal, hence never ⊤. The hypothesis hGfield says only that G is a W^{s,p'} ∩ L² carrier FOR THE SLICE ITSELF; no normalization is performed.