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ChainSizes holds (with n₂ = 0)

Proved
NLogN.KFQ.chainSizes

by xuanji · Oct 17, 2026 · Mathlib 0df444a (Lean v4.33.1)

complexity-theoryinteger-multiplicationkappa-improvement

ChainSizes holds (with n₂ = 0).

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

theorem NLogN.KFQ.chainSizes : ChainSizes

Context. The lemma belongs to the part KFQ: proof of NLogN.KFM.ChainSizes: For n ≥ n₀ and dP n = D + 1:

  • tBD_eq: t_i = 2^{axExp L d i}, hence ∏ t_i = T (prod_tBD) and (∏_{i<D} t_i) · r = T (prod_init);
  • win: the source windows (4d−2)t_i < 4d s_i ≤ (4d−1)t_i, s_i odd;
  • chainSizes : ChainSizes (with n₂ = 0), from params_ok, L_facts, setup_facts, src_facts, srcS_ok_n and the abstract lemmas of KFQArith.

Formalization Note. This lemma belongs to layer 5 of the Lean formalization (integer-multiplication-kappa campaign) of the OpenAI preprint Integer multiplication below nlog⁡nn\log nnlogn: the uniform item-language machine (register programs over the NLogN multitape framework) assembling the Proposition 14 / Lemma 13 / Proposition 18 pieces, the resampling and chirp stages and the cost recurrences into one fixed machine, culminating in NLogN.KFTop.kappa_bound : IntMul.KappaBound (1 / 2 ^ 182) (the bound of Def_IntMul_MultitapeModel). All names refer to the definition bundles up to IntMul_Kappa_K_Defs33.

Preamble
-- OpenAI-preprint / κ-improvement development (integer-multiplication-kappa), generated by skeleton subtraction.

import Definitions.Def_IntMul_Kappa_K_Defs33

set_option autoImplicit false
set_option relaxedAutoImplicit false
set_option maxHeartbeats 1000000

open NLogN
open IntMul IntMul.HvdH IntMul.OpenAI.Glue IntMul.OpenAI.RP NLogN.KFM
set_option maxHeartbeats 1000000
Formal statement
theorem NLogN.KFQ.chainSizes : ChainSizes := by sorry
Source
OpenAI, Integer multiplication below n log n (preprint, 23 Sep 2026), https://github.com/openai/math/tree/adc7f1241b42e322a6451854ab7e4b4c146bf78a/preprints/Integer-multiplication-below-n-log-n-September-23-2026. Lemma `NLogN.KFQ.chainSizes` of the Lean development Solutions/KFQ.lean (lines 88–262), integer-multiplication-kappa campaign.

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