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Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.

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Claim. The answer to Problem 1037 is no. For every large nn divisible by 44 there is a graph on nn vertices with no degree occurring more than twice, at least 34n−O(nlog⁡n)\tfrac34n-O(\sqrt{n\log n}) distinct degrees, that is (34−o(1))n(\tfrac34-o(1))n, and every clique and every independent set on O(log⁡n)O(\log n) vertices; so for every ϵ<14\epsilon<\tfrac14 the hypothesis of the question holds for large nn and no trivial subgraph is larger than a constant times log⁡n\log n. The construction, from the forum comment of 22 September 2025 that wrote it out after a suggestion in the thread the day before and an earlier sketch of 13 September 2025, in the corpus's words: take four copies A,B,C,DA,B,C,D of one realization of the random graph on n/4n/4 vertices with edge probability 12\tfrac12 whose clique and independence numbers are of order log⁡n\log n; list the vertices of A∪BA\cup B as v1,…,vn/2v_1,\dots,v_{n/2} and those of C∪DC\cup D as w1,…,wn/2w_1,\dots,w_{n/2}, each list in decreasing order of degree; join viv_i to wjw_j exactly when i+j≤n/2i+j\le n/2; add every edge between AA and BB and none between CC and DD. The degrees on A∪BA\cup B are then pairwise distinct, and so are those on C∪DC\cup D, so every degree occurs at most twice. Writing b(x)b(x) for the degree of a vertex in its copy of the base graph, viv_i has degree b(vi)+n/4+(n/2−i)b(v_i)+n/4+(n/2-i) and wjw_j has degree b(wj)+(n/2−j)b(w_j)+(n/2-j); the base degrees of the random graph all lie within O(nlog⁡n)O(\sqrt{n\log n}) of n/8n/8, so the degree of wjw_j falls below every degree on A∪BA\cup B once jj exceeds n/4n/4 by more than the spread of the base degrees, which gives at least 34n−O(nlog⁡n)\tfrac34n-O(\sqrt{n\log n}) distinct degrees. The site's commentary and the comment state the count as at least 34n\tfrac34n: the comment assumes without loss of generality that at least half of the base graph's vertices have degree at most (n+1)/8(n+1)/8 and concludes that the degrees of wjw_j for n/4<j≤n/2n/4<j\le n/2 do not appear on A∪BA\cup B; a bound on the base degrees from above alone does not exclude a wjw_j with jj just past n/4n/4 sharing its degree with a viv_i of low base degree, so the comment's justification does not establish the exact count 34n\tfrac34n, and the formalization proves the weaker count (below). A clique or independent set of the whole graph meets each copy in a clique or independent set of the base graph, so both numbers are at most four times those of the base graph. A vertex count not divisible by 44 is handled by adding a few nearly universal vertices. The site credits the construction jointly to Stijn Cambie, Koishi Chan and Zach Hunter.

Depends on. Nothing in this wiki; the argument is self-contained.

Formalization. The file src/v4.29.1/ErdosProblems/Erdos1037.lean of Boris Alexeev's repository lean-proofs (Lean v4.29.1, Mathlib v4.29.1; about 2,200 lines at the pinned commit of 2026-09-15) declares itself a formalization of this construction: its header names Stijn Cambie, Zach Hunter and KoishiChan as informal authors and Aristotle and Boris Alexeev as formal authors, and its docstring describes four copies of a random graph with degrees spread by a cross join. Alexeev announced it in the site's thread on 19 January 2026 as Aristotle's formalization of the proof by Cambie, Hunter and KoishiChan, and added its final theorem the same day after the curator stated the quantifier reading recorded below. The file proves Erdos1037.Theorem_Main: there is a constant CC such that for every 0<ϵ<140<\epsilon<\tfrac14 and every large nn divisible by 44 some graph on Fin n has every degree at most twice, more than (12+ϵ)n(\tfrac12+\epsilon)n distinct degrees, and clique and independence numbers at most Clog⁡nC\log n. Its degree count is num_distinct_degrees_ge: at least 3m−(ΔR−δR)−13m-(\Delta_R-\delta_R)-1 distinct degrees for the graph built on a base graph RR on m=n/4m=n/4 vertices with maximum degree ΔR\Delta_R and minimum degree δR\delta_R, and ΔR−δR≤4mlog⁡m\Delta_R-\delta_R\le4\sqrt{m\log m} for the random base, that is 34n−O(nlog⁡n)\tfrac34n-O(\sqrt{n\log n}); the file does not prove the count 34n\tfrac34n, and the variant cambie_chan_hunter of the formal-conjectures statement file ErdosProblems/1037.lean at the pinned commit, which states 34n\tfrac34n, has proof sorry and no formal_proof attribute. The file also proves Erdos1037.not_erdos_1037, the negation of the statement that for every ϵ>0\epsilon>0 and C>0C>0, every large graph with at least (12+ϵ)n(\tfrac12+\epsilon)n distinct degrees has clique or independence number at least Clog⁡nC\log n. That negated statement carries no hypothesis on degrees occurring at most twice, so it is a weaker negation than the one of the formal-conjectures statement, while Theorem_Main carries the hypothesis. That statement file (not a formalization of the result; the problem page carries its bare pointer) names this file in its formal_proof attribute. The file closes with #print axioms not_erdos_1037 and a comment reporting propext, Classical.choice and Quot.sound. This repository records no build, replay or axiom audit of the file and no review of the fidelity of its statements to the site's question, so the page lists no formalized evidence.

Acceptance. Reviewed: the site's curator, Thomas Bloom, labels the problem DISPROVED (LEAN), credits the construction to the three authors in the commentary (Bloom took no part in it), and in the thread (19 January 2026) fixed the quantifier reading of the question that the construction refutes: for every ϵ>0\epsilon>0 and every C>0C>0, every large graph with at least (12+ϵ)n(\tfrac12+\epsilon)n distinct degrees has a trivial subgraph on more than Clog⁡nC\log n vertices (the problem page's Formulation records this reading with the at-most-twice hypothesis restored). The community database records the problem as disproved. Not refereed: the construction exists only as forum comments, and no paper or preprint of it is known. The gap in the comment's count noted above is this page's own observation; the acceptance rests on the site's acceptance, not on a local review.