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LeanPool.CaffarelliKohnNirenberg.Leray.StabilityWeightedGradientScalar

Stability Weighted Gradient Scalar #

Supporting estimates for the Navier–Stokes development.

theorem CKN.stability_weighted_gradient_scalar {α : Type u_1} [MeasurableSpace α] (μ : MeasureTheory.Measure α) [MeasureTheory.IsFiniteMeasure μ] (F : ℕ → α → ℝ) (G ψ : α → ℝ) (hF : ∀ (n : ℕ), MeasureTheory.MemLp (F n) 2 μ) (hG : MeasureTheory.MemLp G 2 μ) (hψ : MeasureTheory.MemLp ψ ⊤ μ) (hψnonneg : ∀ᵐ (x : α) ∂μ, 0 ≤ ψ x) (hweak : ∀ (w : α → ℝ), MeasureTheory.MemLp w 2 μ → Filter.Tendsto (fun (n : ℕ) => ∫ (x : α), F n x * w x ∂μ) Filter.atTop (nhds (∫ (x : α), G x * w x ∂μ))) :
Filter.Tendsto (fun (n : ℕ) => ∫ (x : α), F n x * G x * ψ x ∂μ) Filter.atTop (nhds (∫ (x : α), G x * G x * ψ x ∂μ)) ∧ ∀ (n : ℕ), 2 * ∫ (x : α), F n x * G x * ψ x ∂μ ≤ ∫ (x : α), F n x * F n x * ψ x ∂μ + ∫ (x : α), G x * G x * ψ x ∂μ

A nonnegative bounded weight converts weak L² convergence into convergence of the mixed energy and a weighted square inequality.