Truly Subquadratic 3SUM and Truly Subcubic APSP
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Deterministic algorithms on a word RAM solve 3SUM in time, Exact Triangle in time, and min-plus matrix multiplication and all-pairs shortest paths in time, for polynomially bounded integer inputs. The development also gives faster weighted-clique algorithms, algorithms for selected entries of thin matrix products, persistent matrix-entry data structures, lopsided triangle detection and counting, and improved algorithms for hinted Boolean matrix-vector problems.
The concepts specify the RAM instructions, step-counting semantics, uniformity in the input size, word-size requirements, and exact input/output conditions. The statements retain the hypotheses of the original formalization: APSP excludes negative cycles, and the hinted-conjecture results make the numerical bounds on rectangular multiplication exponents explicit. Real-RAM and randomized running-time claims are not included.
This is an unofficial Lax packaging of the Lean formalization originally published by Anthropic under Apache-2.0, formalizing work of Josh Alman and Virginia Vassilevska Williams. The original formalization is copyright Anthropic, PBC. Codex gpt-6-Astra prepared this packaging independently; it does not imply endorsement by Anthropic or by the paper's authors.
Concepts
- thm✓
APSP - thm✓
ExactTriangle - thm✓
HintedAlgorithms - thm✓
IntegerAlgorithmBounds - thm✓
LopsidedTriangleAlgorithms - thm✓
MatrixPreprocessing - thm✓
MatrixTradeoffs - thm✓
MinPlusProduct - thm✓
SparseMatrixProduct - thm✓
ThreeSUM - thm✓
WeightedCliqueAlgorithms - thm✓
ZeroWeightClique
- def
CliqueOptimization - def
HintedMatrixVector - def
LopsidedTriangles - def
MatrixParameters - def
PolynomialTime - def
RAMResources - def
ThinMatrices - def
WordRAM
Concept map
Proofs
Proof networkview on GitHub
Proof list
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⊢
Lax350013Proofs.ThreeSumApsp.lax_endStatement_corollary_39_zeroWeight -
⊢
Lax350013Proofs.ThreeSumApsp.lax_endStatement_theorem_22_3SUM -
⊢
Lax350013Proofs.ThreeSumApsp.lax_endStatement_theorem_22_APSP -
⊢
Lax350013Proofs.ThreeSumApsp.lax_endStatement_theorem_22_MinPlus -
⊢
Lax350013Proofs.ThreeSumApsp.lax_wordRam_corollary_26_wanted -
⊢
Lax350013Proofs.ThreeSumApsp.lax_wordRam_corollary_39_min_max -
⊢
Lax350013Proofs.ThreeSumApsp.lax_wordRam_corollary_40_general_times -
⊢
Lax350013Proofs.ThreeSumApsp.lax_wordRam_corollary_40_times -
⊢
Lax350013Proofs.ThreeSumApsp.lax_wordRam_theorem_22_threeSum
Lean sources for these proofs: proofs/ on GitHub
Proof code is not displayed; the archive records each proof's checked relationship between claims.
Related submissions
No other submission in the archive builds on this one, and this one builds on none.
Cite this
This is only the formalizers. The authors of the formalized results may be different (see References).
@misc{lax-350013,
author = {Anthropic, PBC (original formalization) and Codex gpt-6-Astra (Lax packaging)},
title = {Truly Subquadratic 3SUM and Truly Subcubic APSP},
year = {2026},
howpublished = {Lax Archive, lax-350013},
url = {https://laxarchive.org/lax-350013/},
note = {draft},
}
References
- Josh Alman and Virginia Vassilevska Williams. Truly Subquadratic 3SUM and Truly Subcubic APSP via Triangles in Sparse Lopsided Graphs. 2026. arXiv:2610.06783 · arxiv.org/abs/2610.06783v1
- PBC Anthropic. 3SUM and APSP: a Lean 4 formalization. GitHub repository, Apache-2.0, 2026. Commit e1a4e6508154ea59f030480661590a9fe3018011. github.com/anthropics/formal-math/tree/e1a4e6508154ea59f030480661590a9fe3018011/3sum-apsp
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