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LeanPool.Superdiffusion.Algsuperdiff.Section3.Provider.Diffusivity.ApproximateRecurrence.PrincipalResponseSwitchActualShell

PrincipalResponseSwitchActualShell #

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

Provider: the centered fresh shell h - (h)_{z+cu_n} at the frozen W^{2,∞} carrier #

Source displays in ABK26:

What this module supplies #

ApproximateRecurrence.PrincipalResponseSwitchTransport transports the gauge-switch chain to the manuscript's cube z + cu_n, but every one of its statements carries the centered shell h - (h)_{z+cu_n} as an abstract Algsuperdiff.Frozen.Section24.UnitCubeSkewW2Infinity d argument hfield together with two binders about it:

No constructor for that centered object existed in this repository: the proved Provider.BadEvents.incrementUnitCube₂ is the uncentered rescaled increment, and the proved identification of the rescaled coefficient fields (Provider.BadEvents.unitRescaledCutoffCoeff_toCoeffField_ae_eq) is an almost-everywhere statement, while hshift is quantified over every point.

This module builds the constructor and produces both binders.

The construction #

The frozen carrier UnitCubeSkewW2Infinity d stores a value field together with separately stored first and second derivative fields, and every structural obligation on the value field (MemLp ∞, skewness, and HasWeakPartialDerivOn) is an almost-everywhere or distributional statement on the open unit cube. Consequently the value field may be replaced by any almost-everywhere equal field without touching the derivative data. That is unitCubeSkewW2InfinityOfAEEq.

The centered shell is then built in two steps.

  1. subConstShell subtracts a constant antisymmetric matrix from a shell field. A shell field is a triple (value, first derivative, second derivative) with the two HasFDerivAt links and pointwise antisymmetry; subtracting a constant changes only the value, so the derivative data -- and therefore cubeOscGauge, unitCubeDerivNorm, unitCubeSecondDerivNorm and UnitCubeSkewW2Infinity.gradientW1Infinity -- are unchanged definitionally.
  2. centeredShellUnitCube replaces the value field of cubeUnitCube Q (subConstShell hbar _ (shellIncrement omega lowScale highScale)) by the literal difference
    x  |->  a_hi^resc(x) - a_lo^resc(x) - hbar
    
    of the two rescaled coefficient objects. The replacement is legitimate because the two fields agree almost everywhere on the open unit cube, by the proved unitRescaledCutoffCoeff_toCoeffField_ae_eq at both scales together with shellIncrement_apply_eq_cutoff_sub.

Because the value field is now literally that difference, the binder hshift becomes finite algebra on the coefficient carrier: perturbCoeffOn adds t • h to the base field pointwise, so at t = 1 the required identity is a_lo + (a_hi - a_lo - hbar) = a_hi - hbar.

What is produced here, and what is not #

Produced, unconditionally:

Produced, almost surely on the cutoff sample law:

NOT produced here: the shell-size binder hshell, which is the subject of PrincipalResponseSwitchActualShellSize.

Carriers #

Weak partial derivatives are insensitive to the representative #

Homogenization.HasWeakPartialDerivOn U i u g is a family of integral identities in u, so it only sees u through its class modulo null sets of volume.restrict U. CoarseGraining exports the EqOn version of this fact privately in two files; the almost-everywhere version is proved here, in portable style.

Weak partial derivatives are unchanged when the function is modified on a null set of the restricted volume measure.

Unconditional: no caller-supplied proposition enters.

Replacing the value field of a frozen unit-cube W^{2,∞} object #

Representative change at the frozen W^{2,∞} carrier. Given a frozen unit-cube object h and any coefficient field w that agrees with the value field of h almost everywhere on the open unit cube, this is the frozen object whose value field is literally w and whose first and second derivative fields are those of h.

Every structural field of UnitCubeSkewW2Infinity that mentions the value is an almost-everywhere or distributional statement on the open unit cube (MemLp ∞, the skewness of the symmetric part, and HasWeakPartialDerivOn), so all of them transfer.

: this statement holds only under the proposition supplied by its binder hw, the almost-everywhere agreement of the two value fields. It is a provider A, not a source-facing frozen declaration.

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    The representative change does not move the value gauge either: the frozen w1Infinity reads the value field only through an essential supremum.

    Subtracting a constant antisymmetric matrix from a shell field #

    The constant shift of a shell field. A shell field is a triple (value, first derivative, second derivative) subject to two HasFDerivAt links and pointwise antisymmetry; subtracting a constant antisymmetric matrix changes only the value, and preserves all three conditions.

    : this statement holds only under the proposition supplied by its binder hc, the antisymmetry of the constant. It is a provider A, not a source-facing frozen declaration.

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      @[simp]

      The constant shift is invisible to the manuscript's oscillation gauge 3^{2j} ||grad h||_{W^{1,infinity}(z+square_j)}, which reads derivatives only.

      The centered fresh shell at the rescaled unit cube #

      The rescaled centered shell as a shell field: h - hbar transported to the unit cube by the manuscript's map y |-> z + 3^j y.

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        @[simp]
        theorem Algsuperdiff.Section3.Provider.Diffusivity.ApproximateRecurrence.centeredShellField_value {d : ℕ} (Q : HCPolySupport.TriadicCube d) (lowScale highScale : ℤ) (omega : Cutoff.CutoffSample d) (hbar : HCPolySupport.Mat d) (hskew : HCPolySupport.matTranspose hbar = -hbar) (y : HCPolySupport.Vec d) :
        ↑↑(centeredShellField Q lowScale highScale omega hbar hskew).toLInfSkewMatrixFieldOn y = (↑(Stream.shellIncrement (↑omega) lowScale highScale)).1 (3 ^ Q.scale • y + BadEvents.cubeBasePoint Q) - hbar

        The almost-everywhere identification of the rescaled coefficient-field difference with the rescaled centered shell, on the open unit cube.

        This is the two-scale form of the proved Provider.BadEvents.unitRescaledCutoffCoeff_toCoeffField_ae_eq: the constant nu I of a_m = nu I + k_m cancels in the difference, leaving the literal increment k_{highScale} - k_{lowScale}.

        : this statement holds only under the proposition supplied by its binder hle, the manuscript's m - h <= m. It is a provider A, not a source-facing frozen declaration.

        The centered fresh shell h - hbar at the frozen W^{2,∞} carrier.

        Its value field is literally the difference of the two rescaled coefficient objects of PrincipalResponseSwitchTransport, shifted by hbar; its stored derivative fields are those of the rescaled literal increment. The first property makes hshift a pointwise identity; the second makes the frozen gradient gauge equal to that of the uncentered increment.

        : this statement holds only under the propositions supplied by its binders -- hskew (antisymmetry of the centering constant) and hle (m - h <= m). It is a provider A, not a source-facing frozen declaration.

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          The first caller binder: hshift #

          The binder hshift of PrincipalResponseSwitchTransport, produced.

          The manuscript's own field decomposition at the rescaled unit-cube carrier,

          a_{m-h}(z + 3^n .) + (h - (h)_{z+cu_n})  =  a_m(z + 3^n .) - (h)_{z+cu_n} ,
          

          holds at every point, not merely almost everywhere: perturbCoeffOn adds t . h to the base coefficient field pointwise, and the centered shell's value field is by construction the literal difference of the two rescaled coefficient objects.

          Unconditional beyond the binders of centeredShellUnitCube: no further caller-supplied proposition enters.

          The second caller binder: hgrad #

          @[simp]

          Centering by a constant preserves the gradient gauge. The centered shell's frozen gradientW1Infinity is that of the uncentered rescaled increment k_{highScale} - k_{lowScale}.

          Both the constant shift and the representative change leave the stored first and second derivative fields untouched, and gradientW1Infinity reads nothing else, so the identification is definitional.

          Unconditional beyond the binders of centeredShellUnitCube.

          The binder hgrad of PrincipalResponseSwitchTransport, produced.

          Almost surely on the cutoff sample law, membership in the manuscript's own event cQ(n, m-h, z) -- here goodLocalEvent M Ccg Q lowScale at the localization cube Q of scale n and the coarse scale lowScale = m-h -- already gives the discounted gradient gate for the centered shell:

          C_sens ||grad (h - (h)_{z+cu_n})||  <=  3^{-(1/4)(m-h-n)_+} lambda_{3/8,2}(z+cu_n; a_{m-h}) .
          

          This is the proved responseSensitivityConst_mul_gradientW1Infinity_le_of_mem_goodLocalEvent_ae of PrincipalResponseSwitchTransport with its remaining binder hcentered discharged by centeredShellUnitCube_gradientW1Infinity.

          : this statement holds only under the propositions supplied by its binders -- hle (m - h <= m) and hskew -- and the membership hypothesis carried inside the almost-sure conclusion.

          The manuscript's own centering constant #

          The centered fresh shell at the manuscript's own constant (h)_{z+cu_n} = freshShellCubeAverage, whose antisymmetry is the proved freshShellCubeAverage_skew.

          : this statement holds only under the proposition supplied by its binder hle. It is a provider A, not a source-facing frozen declaration.

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            The binder hshift at the manuscript's own centering constant.