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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. Draw the edges of a graph on nn labeled vertices independently with probability p=k/(n2)p=k/\binom n2, where k=12nlog⁡n+12nlog⁡log⁡n+cnnk=\tfrac12n\log n+\tfrac12n\log\log n+c_nn. The probability that the graph contains a Hamiltonian cycle tends to 00 if cn→−∞c_n\to-\infty, to e−e−2ce^{-e^{-2c}} if cn→cc_n\to c, and to 11 if cn→∞c_n\to\infty. This is Theorem 1 of J. Komlós and E. Szemerédi, Limit distribution for the existence of Hamiltonian cycles in a random graph, Discrete Math. 43 (1983), no. 1, 55--63 (received 13 October 1977, revised 1 December 1980; the issue carries the year only, so this page's name uses the first day of it). The paper states on p. 56 that the independent-edge model is equivalent, in this setting, to the uniform choice among all graphs with nn vertices and kk edges, the problem's model, and its Reformulation 1 (p. 57) gives the uniform-model form. The corpus records the paper on its card, which holds no file of it, and pages the theorem at Theorem 1; Theorem 2 (p. 57), the Hamiltonian-path law, is paged at Theorem 2.

For Problem 746: the edge count (12+ϵ)nlog⁡n(\tfrac12+\epsilon)n\log n is kk with cn=ϵlog⁡n−12log⁡log⁡n→∞c_n=\epsilon\log n-\tfrac12\log\log n\to\infty, so the third case gives that the random graph with (12+ϵ)nlog⁡n(\tfrac12+\epsilon)n\log n edges is almost surely Hamiltonian, and Hamiltonicity is preserved by adding edges, which is the site's "≥\ge". The threshold itself had been announced and proved by Korshunov, on his claim page; the paper's abstract credits him with the case cn→∞c_n\to\infty, and Korshunov's 1985 comment calls this paper an independent solution.

Acceptance. Refereed: Discrete Mathematics 43 (1983), no. 1, per the publisher's Crossref record. Reviewed: Erdős cites the paper, then "to appear", as settling the conjecture in his 1981 Combinatorica paper (Part VIII) and his 1982 Singapore paper (§ 1); the site's curator, Thomas Bloom, labels the problem proved and records the limit law in the problem's commentary; Frieze's 2021 bibliography records it. Theorems 1 and 2 are taken as printed and the proof (§§ 1--2) for structure only; the equivalence of the two random-graph models is asserted on p. 56 without argument. This corpus supplies no independent proof review.

Formalization. The file src/latest/ErdosProblems/Erdos746.lean of Boris Alexeev's plby/lean-proofs repository, linked above at a pinned commit, declares itself a Lean formalization of a solution to Erdős Problem 746 and names János Komlós and Endre Szemerédi as informal authors and Codex and GPT-5.6 Sol as formal authors; the note ErdosProblems/Erdos746.md calls it a formalized proof of the problem for Mathlib v4.33.0, and the file was added to the repository on 20 August 2026. Its theorem erdos_746 states that for every ϵ>0\epsilon>0 and every edge-count sequence m(n)m(n) eventually at least (12+ϵ)nlog⁡n(\tfrac12+\epsilon)n\log n and at most (n2)\binom n2, the probability that the uniform random graph with nn vertices and m(n)m(n) edges is Hamiltonian tends to 11, which is the site's statement; the proof goes through an expansion estimate and a sprinkling argument, by the file's own summary, and the file ends with a #print axioms command whose output is not recorded. Because the file names this paper's authors as the informal authors, it is a link on this page and not its own claim; this corpus has not built, audited or kernel-checked it, so it is no formalized evidence.