Smooth periodic tilt functions and their actual integral moments #
This file advances the finite moment calculations in LoopMoments to genuine
smooth functions on the real line, with period 2π and actual interval
integrals. The cosine construction realizes all nonnegative variances. A
separate, explicit amplitude bound is required to preserve the stress
projection. Smoothness in parameters is stated using the amplitude, avoiding
an incorrect claim of smoothness of the square root at zero variance.
The positive exponential tilt used by the manuscript is also treated below. Neither a smooth variance-inversion theorem nor a full true-cone result is assumed or asserted.
Exact moment algebra for the true-cone loop construction #
This file proves the finite-distribution form of the averaging and rephasing
identities in Lemma 6.1 of the candidate manuscript. The formulas are algebraic;
no existence, smoothness, or invertibility of a circle reparametrization is
asserted here. The hypotheses of rephased_moments are ordinary mass, mean,
and variance constraints, not an assumption that a desired loop exists.
The final lemmas give explicit two-point distributions with prescribed variance. They establish finite moment feasibility, including a one-sided support bound.
A finite weighted average. We retain the weights explicitly, so no probabilistic or analytic existence assertion is hidden in the notation.
Equations
- NavierStokes.LoopMoments.avg s w f = ∑ i ∈ s, w i * f i
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The rephasing density relative to the old averaging parameter.
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The positive first component of the loop shear.
Equations
- NavierStokes.LoopMoments.loopA v t = v / (1 + t ^ 2)
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The signed second component; this corresponds to -b_L.
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Reweighting by the manuscript's density has total mass one.
With m = -b/a, the two rephased means are exactly (a,-b).
A two-point probability law. This is a concrete finite object, without any hypothesis asserting the existence of the manuscript's smooth loop.
- leftWeight : ℝ
Left weight of
TwoPoint, of typeℝ. - rightWeight : ℝ
Right weight of
TwoPoint, of typeℝ. - leftValue : ℝ
Left value of
TwoPoint, of typeℝ. - rightValue : ℝ
Right value of
TwoPoint, of typeℝ.
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Mean, given by q.leftWeight * q.leftValue + q.rightWeight * q.rightValue.
Equations
- q.mean = q.leftWeight * q.leftValue + q.rightWeight * q.rightValue
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Centered second, given by q.leftWeight * (q.leftValue - m) ^ 2 + q.rightWeight * (q.rightValue - m) ^ 2.
Equations
- q.centeredSecond m = q.leftWeight * (q.leftValue - m) ^ 2 + q.rightWeight * (q.rightValue - m) ^ 2
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Is probability, given by 0 ≤ q.leftWeight ∧ 0 ≤ q.rightWeight ∧ q.leftWeight + q.rightWeight = 1.
Equations
- q.IsProbability = (0 ≤ q.leftWeight ∧ 0 ≤ q.rightWeight ∧ q.leftWeight + q.rightWeight = 1)
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For any nonnegative variance, equal masses at m ± √V realize it.
Equations
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An asymmetric law preserves a lower bound on the projection p*t,
while allowing any nonnegative variance. For p = 0, use symmetricPair.
The lower projected deviation is -d, and the upper one is V*p²/d.
Equations
- One or more equations did not get rendered due to their size.
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Every mean whose stress projection is strictly above 2 has a finite
two-point distribution with any prescribed nonnegative variance, with both
support points still strictly above that same projection threshold. This is
a feasibility statement for the tilt moments, not the full true-cone test.
The cutoff correction used by the manuscript remains between the old speed and the target speed whenever the old speed is below that target.
A smooth tilt parametrized by its mean and its (signed) amplitude.
Equations
- NavierStokes.SmoothLoop.cosineTilt m amplitude θ = m + amplitude * Real.cos θ
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Smooth parameter data remain smooth when the chosen signed amplitude is
smooth. In particular, a smooth square root of a variance correction can be
used without asserting that square root is smooth on all of [0,∞).
Variance expansion for actual angular integrals.
The normalizing angular mean in the manuscript's exponential family, using cosine instead of sine (a translation of the angular origin).
Equations
- NavierStokes.SmoothLoop.expNormalizer s = NavierStokes.SmoothLoop.angularMean fun (θ : ℝ) => Real.exp (s * Real.cos θ)
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The divided exponential tilt. Its smooth extension at p=0 is handled
separately below; this expression by itself is not that extension.
Equations
- NavierStokes.SmoothLoop.expTilt m d μ p θ = m + d / p * (NavierStokes.SmoothLoop.normalizedExp (μ * p) θ - 1)
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Correct value at vanishing transverse stress. Smooth dependence across
p=0 is a separate analytic obligation; only angular smoothness is proved.
Equations
- NavierStokes.SmoothLoop.extendedExpTilt m d μ p = if p = 0 then NavierStokes.SmoothLoop.cosineTilt m (d * μ) else NavierStokes.SmoothLoop.expTilt m d μ p
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A positive normalized density on a circle, given as a smooth periodic
function on its universal covering line. The construction densityOfTilt
below supplies these data from the already proved moment identity.
Rate of
CircleDensity, of typeℝ → ℝ.- periodic : Function.Periodic self.rate (2 * Real.pi)
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The phase map is an actual global homeomorphism, not an assumed inverse.
Equations
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Rephase, given by f ((phaseHomeomorph d).symm φ).
Equations
- NavierStokes.SmoothLoop.rephase d f φ = f ((NavierStokes.SmoothLoop.phaseHomeomorph d).symm φ)
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Density of tilt, bundling rate, smooth, positive, periodic and the required
compatibility proofs.
Equations
- One or more equations did not get rendered due to their size.
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A complete reparametrization theorem: ordinary mean/variance data produce actual smooth period-one shear functions with the prescribed unweighted integrals. The radial-speed identity is pointwise. No cone condition is included, since that requires further inequalities on the chosen tilts.
Any verified slope condition survives the constructed phase change.
A fully constructed period-one shear loop for arbitrary positive first
mean and nonnegative variance increment. No seed function or inverse is
assumed. The speed increase is exactly the specified ρ.
At zero amplitude the loop shears are exactly the nominal constants, independently of the phase parametrization.