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LeanPool.Superdiffusion.Algsuperdiff.Section4.Provider.Homogenization.HomStepTwoEnergy

HomStepTwoEnergy #

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

Theorem B, §4.5, Step 2a: the energy-from-data display #

The target (Theorem B, Step 2: the energy from data) #

  ν^{1/2} ‖∇u‖_{L²(□_m)}
    ≤ C ( 1 + 𝓔_{1/4,∞,2}(□_m; ã_{L,m}, σ_m) ) ( σ_m^{-1/2} 3^{m/2} + σ_m^{1/2} 3^{m/2} )

proved, per the node's own EDGEs, from the coarse-graining right-hand side and the display bounding the Λ's by the 𝓔's.

What is proved here, exactly #

The two named inputs, composed on the carriers:

The output (exists_sqrt_nu_mul_gradL2_le) is

  ν^{1/2} ‖∇u‖_{L²(□_m)}
    ≤ C(d) t^{-3/2} · σ_m^{-1/2} √(2d) ( 1 + 𝓔_{t/2}(□_m; ã_{L,m}, σ_m) ) · B_g
    + C(d) t^{-1/2} · σ_m^{ 1/2} √(2d) ( 1 + 𝓔_{t}  (□_m; ã_{L,m}, σ_m) ) · B_h

with B_g, B_h CoarseGraining's own note-normalized Besov data quantities at index t (√(2d) is the display bounding the Λ's by the 𝓔's's own dimensional loss, kept visible).

The three deviations from the printed display #

Each is visible in the statement; none is absorbed.

  1. TWO error indices, not one. CoarseGraining's coarse-graining right-hand side places λ at the index t/2 and Λ at the index t (this is confirmed here in the definition of Ch03.dirichletEnergyWithRHSRHS). the display bounding the Λ's by the 𝓔's is therefore instantiated TWICE, at t/2 and at t, and the display carries 𝓔_{t/2} and 𝓔_t separately. Collapsing them to the printed single 𝓔_{1/4} needs an index-monotonicity of 𝓔_{·,∞,2} that is NOT available: Ch02.geometricWeight normalizes the scale weights to a probability distribution, so s ↦ 𝓔_{s,∞,2} is a weighted average whose monotonicity depends on the response sequence. The printed choice 1/4 moreover forces t = 1/2, at which the DATA leg is infinite for C^{0,1/2} data (correction ). RECORDED AS A SOURCE FINDING; the two-index display is the honest one and is what Step 3 can consume.
  2. The t-powers stay displayed: t^{-3/2} and t^{-1/2} are CoarseGraining's own prefactors of the coarse-graining right-hand side. At the §4.5 value t = s = |log γ|⁻¹ they are |log γ|^{3/2} and |log γ|^{1/2}, NOT constants; the source absorbs them into C silently and the node's own NOTE licenses the absorption only because it is spent once. Nothing is absorbed here.
  3. The data legs are CoarseGraining's Besov quantities, not 3^{m/2}. The passage B_g, B_h ≤ C 3^{m/2} is the data embedding, given in the H^s/Gagliardo carrier (HomBridgeDataEmbedding.three_rpow_mul_normalizedGagliardo_originCube_le_ pinned), but CoarseGraining's coarse-graining right-hand side states its data legs in the DYADIC-descendant cubeBesov carrier. The Gagliardo → cubeBesov bridge exists (Provider.ExcessDecay.scaleNormalizedPositiveBesovVectorSeminormTwo_le_ gagliardo); its two side conditions — MemLp g 2 and Gagliardo.MemWsp Q t 2 g from a Hölder bound — do NOT exist and are the exact residue (they are the two Gagliardo-side atoms of the Step-2b family). Since ForceBesovRegularity is ALSO a hypothesis of the coarse-graining right-hand side itself, the two residues are the same two atoms; nothing else is missing.

1. Two rpow spellings #

Disclosed re-derivation: the same two spellings are available in Provider/ExcessDecay/InteriorEllipticity.lean; they are re-proved here (three lines each) to keep this module's import cone off the excess-decay boundary tree, which is under concurrent edit.

2. the display bounding the Λ's by the 𝓔's at CoarseGraining's two ellipticity factors #

The 𝓔-envelope √(2d(𝓔² + 1)) of the display bounding the Λ's by the 𝓔's, at the cube Q, the family A, the index t and the comparator σ Id.

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    the display bounding the Λ's by the 𝓔's, lower half. CoarseGraining's λ_{t,2}^{-1/2} factor is at most σ^{-1/2} √(2d(𝓔_t² + 1)).

    the display bounding the Λ's by the 𝓔's, upper half. CoarseGraining's Λ_{t,2}^{1/2} factor is at most σ^{1/2} √(2d(𝓔_t² + 1)).

    3. The carrier composition: the coarse-graining right-hand side read at the §4.5 data #

    The §4.5 Dirichlet solution, entered into CoarseGraining's Dirichlet carrier at the flux-corrected family ã_{L,m} (the field the source's own remark "the first equation is unchanged if we replace a_L by ã_{L,m}", licenses).

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      4. the energy-from-data display #

      theorem Algsuperdiff.Section4.Provider.Homogenization.exists_sqrt_nu_mul_gradL2_le (d : ℕ) [NeZero d] :
      ∃ (C : ℝ), 0 < C ∧ ∀ (M : Section3.ABKModel d) (L m : ℤ) (omega : Section3.Cutoff.CutoffSample d) {u hdat : HCPolySupport.H1Function (HCPolySupport.openCubeSet (HCPolySupport.originCube d m))} {g : HCPolySupport.Vec d → HCPolySupport.Vec d} {t : ℝ}, Support.IsDirichletSolutionOn (Section3.Cutoff.coefficientCutoff M.nu L omega).toCoeffField (HCPolySupport.originCube d m) u hdat g → 0 < t → t < 1 → (HCPolySupport.Book.Ch03.ForceBesovRegularity (HCPolySupport.originCube d m) t fun (x : HCPolySupport.Vec d) => -g x) → HCPolySupport.Book.Ch03.ForceBesovRegularity (HCPolySupport.originCube d m) t hdat.grad → √M.nu * √(HCPolySupport.Book.Ch03.normalizedSetAverage (HCPolySupport.openCubeSet (HCPolySupport.originCube d m)) fun (y : HCPolySupport.Vec d) => HCPolySupport.vecNormSq (u.grad y)) ≤ (C * t.rpow (-(3 / 2)) * (√(↑(Section3.Annealed.sigmaBar M m))⁻¹ * (√(2 * ↑d) * (1 + HCPolySupport.Book.Ch02.HomogenizationErrorOnCube (HCPolySupport.originCube d m) (t / 2) HCPolySupport.Book.Ch02.MultiscaleExponent.infinity (HCPolySupport.Book.Ch02.MultiscaleExponent.finite 2) (Support.fluxCorrectedCoeffFamily M L m (HCPolySupport.originCube d m) omega) (HCPolySupport.scalarMatrix ↑(Section3.Annealed.sigmaBar M m))))) * HCPolySupport.Book.Ch03.scaleNormalizedPositiveBesovVectorSeminormTwo (HCPolySupport.originCube d m) t fun (x : HCPolySupport.Vec d) => -g x) + C * t.rpow (-(1 / 2)) * (√↑(Section3.Annealed.sigmaBar M m) * (√(2 * ↑d) * (1 + HCPolySupport.Book.Ch02.HomogenizationErrorOnCube (HCPolySupport.originCube d m) t HCPolySupport.Book.Ch02.MultiscaleExponent.infinity (HCPolySupport.Book.Ch02.MultiscaleExponent.finite 2) (Support.fluxCorrectedCoeffFamily M L m (HCPolySupport.originCube d m) omega) (HCPolySupport.scalarMatrix ↑(Section3.Annealed.sigmaBar M m))))) * HCPolySupport.Book.Ch03.scaleNormalizedPositiveBesovVectorNormTwo (HCPolySupport.originCube d m) t hdat.grad

      Step 2a — the energy-from-data display.

      For every §4.5 Dirichlet pair (u, h) with forcing g on □_m, every L, every ω, and every t ∈ (0,1) at which the data are Besov-regular,

        ν^{1/2} ‖∇u‖_{L²(□_m)}
          ≤ C t^{-3/2} · σ_m^{-1/2} √(2d) ( 1 + 𝓔_{t/2,∞,2}(□_m; ã_{L,m}, σ_m) ) · B_g
          + C t^{-1/2} · σ_m^{ 1/2} √(2d) ( 1 + 𝓔_{t,∞,2}  (□_m; ã_{L,m}, σ_m) ) · B_h,
      

      C = C(d) CoarseGraining's dimensional constant of the coarse-graining right-hand side, B_g and B_h the note-normalized Besov data quantities. The association is (σ^{∓1/2}) · (the 𝓔-bracket); the source writes the same product as (1 + 𝓔)(σ^{-1/2}·… + σ^{1/2}·…). See the module docstring for the three disclosed deviations from the printed display.

      5. The error carrier: CoarseGraining's 𝓔 IS the flux-corrected error #

      The 𝓔 appearing in Step 2a is literally the flux-corrected error observable's representative (Support.fluxCorrectedError_characterization, plus isotropicComparatorMatrix σ = scalarMatrix σ by rfl). Recorded so the Step-2a display and EthmB(m) speak of the same random variable.