AI-Discovered Algorithm Delivers First True Subquadratic 3SUM and Subcubic APSP

FrnkNlsn · x · 2026-10-06

An arXiv paper by Josh Alman and Virginia Vassilevska Williams gives the first polynomial improvements over textbook algorithms: deterministic 3SUM in O(n^1.9992) and APSP in O(n^2.9995), refuting the 3SUM and APSP hypotheses plus several related conjectures. The core is a new thin matrix product algorithm modifying Coppersmith-style rectangular multiplication. Per Carl Feynman's account, the algorithm was discovered by AI — someone at Anthropic stumbled on it while asking Claude to solve another problem, then funded two outside researchers to write the paper. Commenters call it a major advance in polynomial complexity.

Related event: Truly Subquadratic 3SUM and Subcubic APSP Break Decades-Old Barriers(7 posts)→

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