Sobolev embedding for whole-space weak families #
A function with a Sobolev family through order k + 2 on ℝ³ has a C^k
representative whose ordered derivatives represent the family, bounded by the
Sobolev norm (lem:lps-Bochner-joint-smooth).
theorem
ESS.lps_integral_sq_sub_small
{a : ℕ → CKN.Foundation.Parabolic.Vec3 → ℝ}
{D : CKN.Foundation.Parabolic.Vec3 → ℝ}
(ha : ∀ (n : ℕ), MeasureTheory.MemLp (a n) 2 MeasureTheory.volume)
(hD : MeasureTheory.MemLp D 2 MeasureTheory.volume)
(hconv : Filter.Tendsto (fun (n : ℕ) => MeasureTheory.eLpNorm (a n - D) 2 MeasureTheory.volume) Filter.atTop (nhds 0))
(ε : ℝ)
:
A square-integrable function that is the L² limit of smooth compactly
supported functions with square-integrable difference a n - a m has
Cauchy square integrals (lem:lps-Bochner-joint-smooth).
theorem
ESS.lps_sobolevNormSq_two_sub_small
{g : ℕ → CKN.Foundation.Parabolic.Vec3 → ℝ}
{D : List (Fin 3) → CKN.Foundation.Parabolic.Vec3 → ℝ}
{k : ℕ}
(hg : ∀ (n : ℕ), ContDiff ℝ (↑⊤) (g n))
(hgc : ∀ (n : ℕ), HasCompactSupport (g n))
(hD : ∀ (α : List (Fin 3)), α.length ≤ k + 2 → MeasureTheory.MemLp (D α) 2 MeasureTheory.volume)
(hconv :
∀ (α : List (Fin 3)),
α.length ≤ k + 2 →
Filter.Tendsto (fun (n : ℕ) => MeasureTheory.eLpNorm (CKN.wordDeriv α (g n) - D α) 2 MeasureTheory.volume)
Filter.atTop (nhds 0))
(α : List (Fin 3))
(hα : α.length ≤ k)
(ε : ℝ)
:
0 < ε →
∃ (N : ℕ),
∀ n ≥ N,
∀ m ≥ N,
(CKN.sobolevNormSqOn 2 Set.univ fun (β : List (Fin 3)) =>
CKN.wordDeriv β (CKN.wordDeriv α fun (x : CKN.Foundation.Parabolic.Vec3) => g n x - g m x)) < ε
The H² norm squared of an ordered derivative of a difference of two members
of an L²-convergent smooth family is eventually small
(lem:lps-Bochner-joint-smooth).