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LeanPool.HighContrastHomogenization.Provider.PolynomialHomogenization.AdaptedCellExcessBoundary

High-contrast homogenization: Provider.PolynomialHomogenization.AdaptedCellExcessBoundary #

Imported from the Apache-2.0 HighContrastHomogenization development at commit 7a13dbcd8d6609264a713373f5c69ceeac870472.

Boundary-row control of an adapted-cell excess #

Filling an adapted cell by Euclidean triadic cells loses one geometric boundary weight per generation. A nonnegative summable majorant for the Euclidean cell excesses therefore controls the excess of the adapted cell by its convolution with that boundary kernel.

theorem HCPolySupport.HighContrast.blockExcess_coarseBlock_adaptedCellAt_le_boundary_tsum {d : ℕ} [NeZero d] {q : Mat d} (hq : Matrix.PosDef q) (k : ℤ) (z : Fin d → ℤ) (a : CoeffSpace d) {F : BlockMat d} (hF : IsSymmetricBlockMat F) (hFpd : Book.Ch02.BlockPosDef F) (B : ℤ → ℝ) (hB0 : ∀ (r : ℤ), 0 ≤ B r) (hBsum : Summable fun (n : ℕ) => 3 ^ (-↑n) * B (k - ↑n)) (hcell : ∀ (r : ℤ) (w : Fin d → ℤ), r ≤ k → standardCell d r w ⊆ adaptedCellAt q k z → blockExcess (coarseBlock (standardCell d r w) a) F ≤ B r) :
blockExcess (coarseBlock (adaptedCellAt q k z) a) F ≤ max 1 (6 * ↑d * √↑d * ‖q⁻¹‖) * ∑' (n : ℕ), 3 ^ (-↑n) * B (k - ↑n)

The excess of an adapted cell is bounded by the Euclidean-cell excess majorant convolved with the geometric boundary kernel. The hypothesis on B is local to cells of at most the target's scale contained in the target, so a containing Euclidean cube can be inserted later without changing this deterministic statement.