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Greedy construction over the first `k` windows (`greedy`)

Proved
J6Sieve.greedy

by xuanji · Oct 19, 2026 · Mathlib 0df444a (Lean v4.33.1)

complexity-theoryinteger-multiplicationkappa-improvement

Greedy construction over the first k windows.

The following holds (Lean statement, in the scope of module Solutions.J6Sieve):

theorem J6Sieve.greedy (d X H : ℕ) (A : ℕ → ℕ) (hA : ∀ i < d, A i + H ≤ X)
    (hH : sieveBound d X < H) :
    ∀ k ≤ d, ∃ s : ℕ → ℕ, (∀ i < k, rough (zz d X) (s i) ∧ A i < s i ∧ s i ≤ A i + H) ∧
      ∀ i < k, ∀ j < k, i ≠ j → Nat.Coprime (s i) (s j)

Context. J6Sieve: pairwise coprime odd numbers in short windows

Elementary (Brun pure sieve + greedy) construction: if d windows (A_i, A_i + H] lie in (0, X] and H > sieveBound d X, one can choose odd, pairwise coprime s_i in them. sieveBound d X < 2 ^ (4 * (log₂ (4 (d (log₂ X + 1) + 1)) + 2)^2).

Formalization Note. Part of the Lean formalization of the round-six κ-improvement (integer-multiplication-kappa campaign, target IntMul.Kappa.jain_round6_framework). The statement is copied verbatim from the Lean development; the platform node carries the same declaration name. Definitions it mentions live in the IntMul_Kappa_R6_Defs* bundles (on top of the published κ bundles IntMul_Kappa_K_Defs*).

Preamble
-- Round-six κ development (integer-multiplication-kappa), generated by skeleton subtraction.

import Definitions.Def_IntMul_Kappa_R6_Defs1

set_option autoImplicit false
set_option relaxedAutoImplicit false
set_option maxHeartbeats 1000000

open J6Sieve
open Finset
Formal statement
theorem J6Sieve.greedy (d X H : ℕ) (A : ℕ → ℕ) (hA : ∀ i < d, A i + H ≤ X)
    (hH : sieveBound d X < H) :
    ∀ k ≤ d, ∃ s : ℕ → ℕ, (∀ i < k, rough (zz d X) (s i) ∧ A i < s i ∧ s i ≤ A i + H) ∧
      ∀ i < k, ∀ j < k, i ≠ j → Nat.Coprime (s i) (s j) := by sorry
Source
S. Jain, round-six networks for the integer-multiplication κ-improvement campaign (https://github.com/Swapnil-jain/integer-mult-kappa, commit 5868dc7) and D. Colkitt, integer-mult-bounds (https://github.com/CrocSwap/integer-mult-bounds); target `IntMul.Kappa.jain_round6_framework`. Lean declaration `J6Sieve.greedy`, Solutions/J6Sieve.lean (lines 24–75) of the round-six development.

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