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LeanPool.CaffarelliKohnNirenberg.Core.Step4.PressureGradientGluedOriginClause

The every-cell bound of the origin carrier, at the margin scale #

The origin-carrier cell output asks for a bound on every Morrey cell of the selected pressure gradient, at every centre and every positive radius. The one-sided transfer supplies it from two inputs: a growth bound on cells below a fixed scale ρ₀, and the total integral on the carrier cylinder. The scale ρ₀ is a free parameter of that transfer, and choosing it is exactly the choice of where the two regimes meet.

Choosing ρ₀ = R₁, the radius of the carrier itself, makes the small-cell input impossible to supply, for two independent reasons.

Choosing instead the margin scale ρ₀ = (1 - R₁) / 4 removes both. The region the domain hypothesis controls is the closed unit cylinder, so the governing margin is the one between the carrier radius R₁ and 1, not the one between R₁ and R₀. At that scale 3 * r ≤ 1 - R₁, so a cell meeting the carrier has its doubled ball inside the unit ball; and r ≤ 1/4, so (2 * r) ^ 2 ≤ 1/4 and every doubled window stays inside Ioc (-1) 0. Cells at or above the margin scale are not reached by the slice estimate at all and are bounded by the total integral on the carrier, with the explicit scale factor that the one-sided transfer constant carries.

The margin scale must not be allowed to degenerate. Because R₁ < 3/4, the scale (1 - R₁) / 4 lies in [1/16, 1/4), bounded away from zero uniformly in the admissible data. A scale proportional to R₀ - R₁ would not be: by oneSidedMorreyBound_scale_eq, measuring the transfer constant at a scale ρ₀ instead of at R₁ inflates the whole-carrier constant by exactly (R₁ / ρ₀) ^ (5 (1 - (6/5)/κ)), and with ρ₀ = (R₀ - R₁) / 3 that factor is unbounded as R₁ ↑ R₀, which would make the comparison with the explicit majorant of the estimate unsatisfiable at the top of the admissible range. At ρ₀ = (1 - R₁) / 4 the factor is at most 12 ^ (5 (1 - (6/5)/κ)).

Nothing else in the estimate changes: the transfer, the carrier, the field and the conclusion are the established ones.

theorem CKN.Core.Step4.originMarginScale_lt_quarter {R₁ : ℝ} (hR₁ : 0 < R₁) :
(1 - R₁) / 4 < 1 / 4

The margin scale of the origin carrier is below a quarter, which is what keeps every doubled window inside the unit time interval.

theorem CKN.Core.Step4.originMarginScale_pos {R₁ : ℝ} (hR₁ : R₁ < 1) :
0 < (1 - R₁) / 4

The margin scale of the origin carrier is positive, and in fact at least 1/16 on the admissible range R₁ < 3/4: it does not degenerate.

theorem CKN.Core.Step4.originMarginScale_lower_bound {R₁ : ℝ} (hR₁quarter : R₁ < 3 / 4) :
1 / 16 < (1 - R₁) / 4

The margin scale of the origin carrier is bounded below uniformly in the admissible data. This is what keeps the comparison with the explicit majorant of the estimate from degenerating.

theorem CKN.Core.Step4.originMarginScale_double_sq_le {R₁ r : ℝ} (hR₁ : 0 < R₁) (hr : 0 < r) (hmargin : r ≤ (1 - R₁) / 4) :
(2 * r) ^ 2 ≤ 1 / 4

At the margin scale the doubled radius is still small enough for the time-side inclusion.

theorem CKN.Core.Step4.originMarginScale_triple_le {R₁ r : ℝ} (hR₁ : R₁ < 1) (hmargin : r ≤ (1 - R₁) / 4) :
3 * r ≤ 1 - R₁

At the margin scale a cell meeting the carrier has its doubled ball inside the unit ball.

theorem CKN.Core.Step4.margin_cell_window_subset_unit_time {r : ℝ} {z : Foundation.Parabolic.ParabolicPoint} (hz : z ∈ Foundation.Parabolic.parabolicCylinder 0 0 (3 / 4)) (hr2 : (2 * r) ^ 2 ≤ 1 / 4) :
Set.Ioc (z.2 - (2 * r) ^ 2) z.2 ⊆ Set.Ioc (-1) 0

Every window of a margin-scale cell lies inside the unit time interval. This is the satisfiability certificate of the small-cell regime: the data hypotheses of the estimate control the solution only on Ioc (-1) 0, and a cell centred anywhere in the cylinder of admissible centres, at a radius at most the margin scale, never reaches outside that interval.

theorem CKN.Core.Step4.originCellOutput_of_margin_cell_bounds {R₁ κ ρ₀ : ℝ} {A B : ENNReal} {Dp : Foundation.Parabolic.ParabolicPoint → Foundation.Parabolic.Vec3} (hR₁ : 0 < R₁) (hR₁quarter : R₁ < 3 / 4) (hκ : 6 / 5 ≤ κ) (hρ₀ : 0 < ρ₀) (hsmall : ∀ (i : Fin 3), ∀ z ∈ Foundation.Parabolic.parabolicCylinder 0 0 (3 / 4), ∀ (r : ℝ), 0 < r → r ≤ ρ₀ → Foundation.Parabolic.Morrey.cylinderPowerIntegral (6 / 5) (fun (w : Foundation.Parabolic.ParabolicPoint) => Dp w i) z r ≤ A * ENNReal.ofReal (r ^ (5 * (1 - 6 / 5 / κ)))) (hglobal : ∀ (i : Fin 3), ∫⁻ (w : Foundation.Parabolic.ParabolicPoint) in Foundation.Parabolic.parabolicCylinder 0 0 R₁, ENNReal.ofReal |Dp w i| ^ (6 / 5) ≤ B) :

The origin-carrier cell output from the two regimes, with the small-cell input taken only below a free scale ρ₀. The centres are the ones the one-sided transfer consumes, so the statement composes with the established transfer without change; only the radius threshold moves from R₁ to ρ₀.

theorem CKN.Core.Step4.originCellProducer_of_margin_past_slice_data (hPast : ∀ (q τ C_CZ R₀ R₁ ε : ℝ) (KU KD : ENNReal), 5 / 2 < q → 25 / 3 ≤ τ → τ ≤ 25 → 0 ≤ C_CZ → 0 < R₁ → R₁ < R₀ → R₀ < 3 / 4 → 0 ≤ ε → KU < ⊤ → KD < ⊤ → ∀ {Ω : Set Foundation.Parabolic.Vec3} {I : Set ℝ} {u : Foundation.Parabolic.ParabolicPoint → Foundation.Parabolic.Vec3} {Du : Foundation.Parabolic.ParabolicPoint → Fin 3 → Foundation.Parabolic.Vec3} {p : Foundation.Parabolic.ParabolicPoint → ℝ} {f : Foundation.Parabolic.ParabolicPoint → Foundation.Parabolic.Vec3}, IsSuitableWeakSolutionIntegrable Ω I q u Du p f → closure (Foundation.Parabolic.parabolicCylinder 0 0 1) ⊆ spaceTimeSet Ω I → (∀ (i : Fin 3), Foundation.Parabolic.Morrey.morreyNorm 3 τ ((Foundation.Parabolic.parabolicCylinder 0 0 R₀).indicator fun (z : Foundation.Parabolic.ParabolicPoint) => u z i) ≤ KU) → (∀ (i j : Fin 3), Foundation.Parabolic.Morrey.morreyNorm 2 (25 / 8) ((Foundation.Parabolic.parabolicCylinder 0 0 R₀).indicator fun (z : Foundation.Parabolic.ParabolicPoint) => Du z i j) ≤ KD) → ∫⁻ (z : Foundation.Parabolic.ParabolicPoint) in Foundation.Parabolic.parabolicCylinder 0 0 1, ENNReal.ofReal (Foundation.Parabolic.vec3EuclideanNorm (u z)) ^ 3 + ENNReal.ofReal |p z| ^ (3 / 2) + ENNReal.ofReal (Foundation.Parabolic.vec3EuclideanNorm (f z)) ^ q ≤ ENNReal.ofReal ε → ∃ (Dp : Foundation.Parabolic.ParabolicPoint → Foundation.Parabolic.Vec3), (∀ (i : Fin 3), AEMeasurable (fun (z : Foundation.Parabolic.ParabolicPoint) => Dp z i) (MeasureTheory.volume.restrict (Foundation.Parabolic.vec3Ball 0 R₁ ×ˢ I))) ∧ (∀ (U : Set Foundation.Parabolic.Vec3) (J : Set ℝ), localBox Ω I U J → U ⊆ Foundation.Parabolic.vec3Ball 0 R₁ → ∀ (i : Fin 3), MeasureTheory.Integrable (fun (z : Foundation.Parabolic.ParabolicPoint) => Dp z i) (MeasureTheory.volume.restrict (spaceTimeSet U J))) ∧ (∀ (i : Fin 3), ∀ ψ ∈ spaceTimeTestFunction Set.univ Set.univ, tsupport ψ ⊆ Foundation.Parabolic.vec3Ball 0 R₁ ×ˢ I → ∫ (z : Foundation.Parabolic.ParabolicPoint), p z * spatialPartial ψ i z = -∫ (z : Foundation.Parabolic.ParabolicPoint), Dp z i * ψ z) ∧ ∃ (A : ENNReal) (B : ENNReal), (∀ (i : Fin 3), ∀ z ∈ Foundation.Parabolic.parabolicCylinder 0 0 (3 / 4), ∀ (r : ℝ), 0 < r → r ≤ (1 - R₁) / 4 → Foundation.Parabolic.Morrey.cylinderPowerIntegral (6 / 5) (fun (w : Foundation.Parabolic.ParabolicPoint) => Dp w i) z r ≤ A * ENNReal.ofReal (r ^ (5 * (1 - 6 / 5 / min (1 / τ + 8 / 25)⁻¹ q)))) ∧ (∀ (i : Fin 3), ∫⁻ (w : Foundation.Parabolic.ParabolicPoint) in Foundation.Parabolic.parabolicCylinder 0 0 R₁, ENNReal.ofReal |Dp w i| ^ (6 / 5) ≤ B) ∧ Endgame.oneSidedMorreyBound (6 / 5) (min (1 / τ + 8 / 25)⁻¹ q) ((1 - R₁) / 4) A B ≤ oneSidedPressureGradientKP q τ C_CZ R₀ R₁ ε KU KD) :

The origin-carrier cell producer from margin-scale past-cylinder slice data. This is the established past-slice route with the growth clause taken only at the margin scale, where it is supplyable, and with the resulting transfer constant compared against the explicit majorant of the estimate. The field is bound before every clause that mentions it, and the two integral constants are bound with it.