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LeanPool.Superdiffusion.Algsuperdiff.Section4.Provider.ExcessDecay.LambdaCaps

LambdaCaps #

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

The coarse-grained ellipticity ratios of the flux-corrected field #

This module renders the two ratios of e.bound.Lambdas.by.Es.v2 (ABK26) at the proved Section 4 carriers, and bounds their maximum by the flux-corrected homogenization error 𝓔_{s,∞,2}. It is the Λ-side companion of the good-event caps chain assembled in GoodEventCaps.lean.

What is proved, and what is not #

The printed Section 2 lemma l.mathcal.E.to.Lambdas (display e.bound.Lambdas.by.Es) asserts the sharp, dimension-free two-sided comparison

½ 𝓔_{s,∞,q}(□_m; a, σ₀)²
  ≤ max{ σ₀⁻¹ Λ_{s,q}(□_m; a) , σ₀ λ_{s,q}⁻¹(□_m; a) }
  ≤ 1 + 2 𝓔_{s,∞,q}(□_m; a, σ₀)² + 2^{1/2} 𝓔_{s,∞,q}(□_m; a, σ₀) .

Only the upper half is treated here, and only in a 2d-lossy form: max{…} ≤ 2d (𝓔² + 1) at q = 2. This is not the printed statement and must never be presented as l.mathcal.E.to.Lambdas:

The lossy form suffices for the only §4.3 consumption site: the good-event cap needs a bound by a constant C(d), and 2d(𝓔²+1) with 𝓔 capped is such a constant.

Main definitions #

Main results #

Carrier conventions used (resolution A4) #

Every cube is the origin cube originCube d k; a statement at z + □_k is obtained by translating the sample, i.e. by evaluating at Cutoff.translateCutoffSample z omega. The comparator is σ_k Id = isotropicComparatorMatrix (Annealed.sigmaBar M k), which is CoarseGraining's scalarMatrix (σ_k : ℝ) on the nose.

References #

1. The two ratio carriers at the flux-corrected field #

Λ_{s,2}(□_k; a_L − (κ_L − κ_k)_{□_k}), as a function of the cutoff sample. The value at z + □_k is this function at Cutoff.translateCutoffSample z omega (resolution A4).

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    λ_{s,2}⁻¹(□_k; a_L − (κ_L − κ_k)_{□_k}). The manuscript always writes the inverse lower constant, and so does the proved Section 3 observable Observable.cutoffLowerEllipticityInvLiteral; this is the same reading at the flux-corrected field.

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      The left-hand side of e.bound.Lambdas.by.Es.v2, taken at the single comparator σ_k on both legs.

      We follow the lemma, i.e. the mathematically supported reading, and take σ₀ = σ_k at the cube □_k that carries the functional.

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        2. The 2d-lossy upper half at CoarseGraining's carriers #

        The upper half of e.bound.Lambdas.by.Es, in its 2d-lossy q = 2 form. Transport of CoarseGraining's Ch02.max_weightedEllipticity_finite_two_le_card_mul_homogenizationError_sq_add_one with Fintype.card (Fin d) evaluated.

        This is not the printed lemma: the printed right-hand side is the dimension-free 1 + 2𝓔² + 2^{1/2}𝓔. See the module docstring.

        3. Transport to the flux-corrected sample carrier #

        The ratio maximum at the flux-corrected field, bounded by the literal flux-corrected error. Pointwise in the sample; no probability enters.

        The almost-everywhere form at the measurable representative, uniformly in L ≥ k.

        The passage from the literal error to Support.fluxCorrectedErrorRepresentative is the proved Support.ae_forall_fluxCorrectedError_eq_representative, which carries all L ≥ k on a single probability-one event because the index set is countable.

        4. The folding step #

        theorem Algsuperdiff.Section4.Provider.ExcessDecay.two_mul_dim_mul_sq_add_one_le_of_le {d : ℕ} {E t : ℝ} (hE : 0 ≤ E) (hEt : E ≤ t) :
        2 * ↑d * (E ^ 2 + 1) ≤ 2 * ↑d * (t ^ 2 + 1)

        The cap-folding step. An 𝓔-bound 𝓔 ≤ t turns the envelope 2d(𝓔² + 1) into the constant 2d(t² + 1). This is the arithmetic the good-event cap performs after the annular anchor has supplied t.