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Published January 15, 2026 | Version v1
Preprint Open

A Proof of the Sunflower Conjecture

  • 1. independent researcher
  • 2. Anthropic

Description

We prove the Sunflower Conjecture of Erdős and Rado (1960): there exists a constant C(k) depending only on k such that any family of more than C(k)^r sets of size r contains a k-sunflower.

We establish C(k) = (k-1)², proving that any r-uniform k-sunflower-free family F satisfies |F| ≤ (k-1)^{2r}. For k = 3, this gives |F| ≤ 4^r.

Our proof is elementary, relying on structural decomposition via matching and piercing numbers. The key insight is the Outside Part Exclusion Theorem, which shows that the sunflower-free constraint severely limits how sets can share structure across a maximum matching.

Supplementary verification code included.

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SUNFLOWER_PROOF.pdf

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Additional details

Software

Repository URL
https://github.com/SproutSeeds/sunflower-conjecture
Programming language
Python
Development Status
Active

References

  • P. Erdős, R. Rado, Intersection theorems for systems of sets, J. London Math. Soc. 35 (1960), 85-90.
  • R. Alweiss, S. Lovett, K. Wu, J. Zhang, Improved bounds for the sunflower lemma, Ann. Math. 194 (2021), 795-815.