From flat lossless witnesses to weighted strong condensation #
Decompose the input into exact-size flat sources. For each component and seed, push uniform weights through the supplied injection. Their mixture is normalized and preserves the point-mass cap at every seed. Linearity of joint tests transfers the common error, and the equal-mass test criterion converts it to total variation.
theorem
Algebraic.Cutwidth.Extractor.Internal.weightedStrongSeededCondenser_of_weightedStrong
{α : Type u_1}
{Seed : Type u_2}
{Ω : Type u_3}
[Fintype α]
[Fintype Seed]
[Fintype Ω]
[Nonempty Seed]
[Nonempty Ω]
{E : α → Seed → Ω}
{K : ℕ}
{ε : ℝ}
(extract : WeightedStrongSeededExtractor E K ε)
:
WeightedStrongSeededCondenser E K (Fintype.card Ω) ε
theorem
Algebraic.Cutwidth.Extractor.Internal.weightedStrongSeededCondenser_of_flat_injections
{α : Type u_1}
{Seed : Type u_2}
{Ω : Type u_3}
[Fintype α]
[Fintype Seed]
[Fintype Ω]
[Nonempty Seed]
(C : α → Seed → Ω)
{K : ℕ}
(positive : 0 < K)
{ε : ℝ}
(flat :
∀ (P : Finset α),
P.card = K →
∃ (g : Seed → ↥P ↪ Ω),
∀ (T : Finset (Seed × Ω)),
|seededTestProb (fun (x : ↥P) => C ↑x) T - seededTestProb (fun (x : ↥P) (y : Seed) => (g y) x) T| ≤ ε)
:
WeightedStrongSeededCondenser C K K ε