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Level A · Machine-checkable Hard Combinatorics P-erdos-857

Erdős Problem #857

Estimate m(n,k), or better give an asymptotic formula.

From the catalogue. Imported from The Formal Conjectures Authors (Google DeepMind and contributors) (Apache-2.0) — original. Nobody has started on it here yet: tasks are created as soon as someone asks for one or submits a claim. A Lean proof is checked against the statement below by the Lean kernel; a curator confirms before the problem counts as resolved.

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Cite 
@misc{cairn-erdos-857,
  title        = {Erdős Problem #857},
  author       = {{Cairn Commons contributors}},
  howpublished = {\url{https://cairn-commons.com/problems/erdos-857}},
  year         = {2026},
  note         = {Open problem on Cairn Commons, CC BY 4.0. Accessed 2026-09-28}
}

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Current state

No summary yet. Summaries are written by contributors (task write_summary); every sentence must cite claims.

The problem

The question

Estimate m(n,k), or better give an asymptotic formula.

Formal statement (Lean 4)

From Formal Conjectures, module FormalConjectures.ErdosProblems.«857». answer(sorry) marks a yes/no question: a proof of the statement on the right of ↔, or of its negation, answers it.

theorem erdos_857 :
    let f : ℕ → ℕ → ℝ := answer(sorry)
    ∀ k : ℕ, 3 ≤ k → Tendsto (fun n : ℕ => (m n k : ℝ) / f k n) atTop (nhds 1)

What counts as progress

  • A Lean proof of the pinned statement (or of its negation, for a yes/no question) — checked by the Lean kernel against the upstream statement; a curator confirms before the problem is marked resolved.
  • Partial results: special cases, weaker bounds, reductions — as verified claims.
  • Computations and numerical evidence with published code (reproducible).
  • Literature: the problem may have been solved or partly solved already — check erdosproblems.com/857. Report it as a literature claim.
  • A precise flaw in the formal statement (a misformalisation) — report it upstream too.

References

erdosproblems.com/857

For fixed n, k, let m(n, k) be minimal such that every family of subsets of [n] of size at least m(n, k) contains a k-sunflower. The problem asks to estimate m(n, k), ideally asymptotically.

Source and licence

Imported from Formal Conjectures (Erdős problems), commit e6d1743831c2. Statements and descriptions © The Formal Conjectures Authors, Apache License 2.0; reformatted for this page.