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The pruned thin-product program at c = 21.2733, θ = 0.111731 solves the thin matrix product on all instances

Proved
Light.Filter.allInstancesF_programF

by xuanji · Oct 7, 2026 · Mathlib 0df444a (Lean v4.33.1)

apsp-2996001apsp-exponentfine-grained-complexityword-ram

Procedure 747474 (allInstancesF) of the program programF solves the thin matrix product task thinTask within allInstancesTimeF c₃₀ steps and with need allInstancesNeedF:

for an instance xxx with parameters N,D,w,UN, D, w, UN,D,w,U (two integer matrices X∈ZN×DX\in\mathbb Z^{N\times D}X∈ZN×D, Y∈ZD×NY\in\mathbb Z^{D\times N}Y∈ZD×N with entries bounded by UUU and www wanted positions (ik,jk)(i_k,j_k)(ik​,jk​)), the call writes the www entries ∑t<DXiktYtjk\sum_{t<D}X_{i_k t}Y_{t j_k}∑t<D​Xik​t​Ytjk​​ to the output area and changes no other cell below the free pointer. The time is 30000+toff(N,D,w)30000+t_{\mathrm{off}}(N,D,w)30000+toff​(N,D,w) when D1249≤N71D^{1249}\le N^{71}D1249≤N71, where tofft_{\mathrm{off}}toff​ is the time tOffline32P of the offline routine of Corollary 32 with pruned encodings at the rational parameters ratParamsF (c=212733/10000c=212733/10000c=212733/10000, θ=111731/106\theta=111731/10^6θ=111731/106), and 30000+40(w+1)(D+1)30000+40(w+1)(D+1)30000+40(w+1)(D+1) (brute force) otherwise.

programF is program31P ratParamsF (the programs of Section 4 with pruned encodings, Corollaries 31-32) followed by allInstancesF (number 74), which tests D1249≤N71D^{1249}\le N^{71}D1249≤N71 with regimeTestF (number 75).

“Procedure ppp of program PPP solves the task within TTT steps with need ν\nuν” (SolvesN) means: in every program that begins with PPP, for every instance and every memory satisfying the task's precondition, and all limits (word size, cells, call depth) allowing ν\nuν of the instance's parameters, the call of ppp with the instance's arguments ends within TTT of the parameters steps and leaves a memory satisfying the postcondition.

Preamble
/-
Copyright (c) 2026 Anthropic, PBC. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
SPDX-License-Identifier: Apache-2.0
-/
-- Generated by skeleton subtraction from the ThreeSumApsp library at commit 7c34437be804.

import Definitions.Def_APSP2996001_Defs2

set_option autoImplicit false
set_option relaxedAutoImplicit false

open Light
open Light.Filter
open ThreeSumApsp ThreeSumApsp.Spec Light.Sec4
Formal statement
theorem Light.Filter.allInstancesF_programF : SolvesN thinTask programF Proc.allInstancesF
    (allInstancesTimeF cShared30) allInstancesNeedF := by sorry
Source
Developed for the prove2.me APSP exponent campaign (https://prove2.me/campaigns/apsp-exponent) on top of the Lean formalization anthropics/formal-math, folder 3sum-apsp, commit e1a4e65 (https://github.com/anthropics/formal-math/tree/e1a4e6508154ea59f030480661590a9fe3018011/3sum-apsp; Lean v4.33.1, Mathlib v4.33.1). The statement comes from the file 3sum-apsp/ThreeSumApsp/Filter/ThinAll.lean of the campaign's modified copy of that library, which is not published; the new definitions it uses are in the platform definition bundles APSP2996001_Defs1 and APSP2996001_Defs2 (and APSP299791_Defs1 to APSP299791_Defs5 of the 2.99791 entry). It follows the technical note "Deterministic APSP via thin products" (6 October 2026) refining J. Alman and V. Vassilevska Williams, "Truly Subquadratic 3SUM and Truly Subcubic APSP via Triangles in Sparse Lopsided Graphs", arXiv:2610.06783v1 (https://arxiv.org/abs/2610.06783v1), Lemma 5.1 (the thin product at c = 21.2733, θ = 0.111731).

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