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LeanPool.CaffarelliKohnNirenberg.Core.Endgame.OneSidedCover

Finite one-sided coverings and total integral estimates #

A finite metric-ball cover of the closed intermediate cylinder gives a finite backward-cylinder cover after truncating the forward time shifts. All centers and the number of cylinders are chosen before the integrand.

theorem CKN.Core.Endgame.exists_finite_one_sided_cylinder_cover_on_cylinder (a ρ₀ : ℝ) (ha : 0 < a) (ha34 : a < 3 / 4) (hρ₀ : 0 < ρ₀) :

At every prescribed positive scale, finitely many cylinders of half that radius, with admissible centers, cover the intermediate cylinder. The selected centers depend only on the scale and the fixed geometry.

A finite geometric multiplicity turns uniform small-cylinder integral bounds into a total bound on the intermediate cylinder. The integer is chosen before the integrand or its bound, so its dependence is only on the fixed geometry and ρ₀.

A geometric multiplicity bounds the total integral on the fixed cylinder.