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Problem 36

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claims/: The 6 claim pages of Problem 36, one per claimant's result; the problem's standing derives from them.


Statement. Find the optimal constant c>0c>0 such that the following holds.

For all sufficiently large NN, if A⊔B={1,…,2N}A\sqcup B=\{1,\ldots,2N\} is a partition into two equal parts, so that ∣A∣=∣B∣=N\lvert A\rvert=\lvert B\rvert=N, then there is some xx such that the number of solutions to a−b=xa-b=x with a∈Aa\in A and b∈Bb\in B is at least cNcN.

Status. Open, the site's label (OPEN; page last edited 23 January 2026). The site's commentary gives the records 0.379005<c<0.3808760.379005<c<0.380876, the lower bound due to White [Wh22] and the upper bound to the TTT-Discover LLM [YKLBMWKCZGS26], improving on AlphaEvolve [GGTW25] and Haugland [Ha16]. The record bounds and the later bounds with library cards have partial claim pages: White's refereed lower bound (claim page, accepted on the refereed publication), the TTT-Discover upper bound (claim page, claimed), Kim and Pilanci's lower bound 0.379120.37912 of June 2026 (claim page, claimed) and Russell's certified upper bound 0.380859060.38085906 of July 2026 (claim page, claimed). The site's proof-claims tab carries two partial proof claims, each raising the lower bound for the constant: one submitted by Liam Price on 2026-07-20 and credited to GPT Pro, claiming c≥0.38055470c\ge0.38055470 (claim page), and one submitted by the forum user Drynshock on 2026-09-19 and credited to GPT 6 Pro, claiming c>0.3805634c>0.3805634 through a subadditivity inequality for the overlap function added to the convex relaxation (claim page); neither claim had comments on its thread as of 2026-10-06, and this page records them without adopting them. The superseded bounds, the trivial 1/41/4, Scherk's 1−1/21-1/\sqrt2, Moser's 4−15≈0.3564\sqrt{4-\sqrt{15}}\approx0.3564, Haugland's upper bounds of 1996 and 2016 and AlphaEvolve's 0.3809240.380924, are history recorded in the references and get no claim page.

Source. erdosproblems.com/36, accessed 2026-09-04. Cite as: T. F. Bloom, Erdős Problem #36, https://www.erdosproblems.com/36.

References.

  • [GGTW25] B. Georgiev, J. Gómez-Serrano, T. Tao, and A. Wagner, Mathematical exploration and discovery at scale. arXiv:2511.02864 (2025).
  • [Gu04] Guy, Richard K., Unsolved problems in number theory. 3rd ed., Problem Books in Mathematics, Springer, New York (2004), xviii+437 pp. Section C17 "The minimum overlap problem", printed p. 199: the definition of MM as min⁡max⁡kMk\min\max_kM_k over the partitions of {1,…,2n}\{1,\ldots,2n\}, Erdős's M>n/4M>n/4 with the improvements of Scherk, Świerczkowski and Leo Moser, the Motzkin--Ralston--Selfridge examples with M<2n/5M<2n/5 "contrary to Erdős's conjecture that M=12nM=\frac12n", the question "Is there a number cc such that M∼cnM\sim cn?", the table of M(n)M(n) for n≤15n\le15, and Haugland's lim⁡M(n)/n≤0.38200298812318988…\lim M(n)/n\le0.38200298812318988\ldots. Library home: guy_2004_unsolved_problems_number_theory.
  • [Ha16] Haugland, J. K., The minimum overlap problem revisited. arXiv:1609.08000 (2016).
  • [Wh22] White, E. P., Erdős' minimum overlap problem. arXiv:2201.05704 (2022). Published as A new bound for Erdős' minimum overlap problem, Acta Arith. 208 (2023), no. 3, 235-255, doi:10.4064/aa220728-7-6. Library home: white_2022_erdos_minimum_overlap_problem.
  • [YKLBMWKCZGS26] M. Yuksekgonul, D. Koceja, X. Li, F. Bianchi, J. McCaleb, X. Wang, J. Kautz, Y. Choi, J. Zou, C. Guestrin, and Y. Sun, Learning to Discover at Test Time. https://test-time-training.github.io/discover.pdf (2026).

Formalization. Statement in formal-conjectures at its revision of 2026-10-06, the one linked, which states the limit as erdos_36 with answer(sorry) and a sorry body and carries no formal_proof attribute; its variants record the published lower and upper bounds and neither claimed bound above.

Progress

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Known Results

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Linked library material

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