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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 conjecture of Problem 1078 holds. In the transversal language of the problem page, with Δ(r,n)\Delta(r,n) the largest integer such that every rr-partite graph with parts of size nn and maximum degree below it has an independent transversal and Δr=lim⁡nΔ(r,n)/n\Delta_r=\lim_n\Delta(r,n)/n, the note proves Δr≥12\Delta_r\ge\frac12 for every rr; by the complementation written on the problem page, cr=(r−1)−Δr≤r−32c_r=(r-1)-\Delta_r\le r-\frac32 for every r≥3r\ge3, where crc_r is the limit of fr(n)/nf_r(n)/n and fr(n)f_r(n) the largest minimum degree of a KrK_r-free rr-partite graph whose parts all have size nn. With the 1975 lower bound cr≥r−32−1r−2c_r\ge r-\frac32-\frac1{r-2} for r>4r>4 (the construction printed on p. 105 of the 1975 paper; p. 98 states it with 12(r−2)\frac1{2(r-2)}) this gives lim⁡r→∞(cr−r+2)=12\lim_{r\to\infty}(c_r-r+2)=\frac12, the conjecture of Bollobás, Erdős and Szemerédi that the site's statement renders with its o(1)o(1). The claimed result is the theorem of P. E. Haxell, A note on vertex list colouring, Combin. Probab. Comput. 10 (2001), no. 4, 345--347, which its abstract states in list-coloring form: if every vertex has a list of 2k2k colors and each color appears on the lists of at most kk neighbors of any vertex, a proper coloring from the lists exists, which the abstract calls a weak form of a conjecture of Reed. The note is not held, so the exact finite form of its transversal statement is recorded here from the later account of Haxell and Szabó, the claimant's own, which says that the note improved the bound to Δr≥12\Delta_r\ge\frac12 and settled the 1975 conjecture; the sharp finite threshold is the later theorem on the claim page Haxell and Szabó.

Depends on. Nothing in this wiki beyond the complementation written on the problem page, which turns the transversal bound into the degree threshold.

Acceptance. Refereed: Combinatorics, Probability and Computing (the Crossref record: volume 10, issue 4, pp. 345--347, issued July 2001, online 2 October 2001; the day is the issue's nominal first day, used for this page's date). Reviewed: the site's curator, T. F. Bloom, labels the problem proved and names this note as the proof. The refereed paper of Haxell and Szabó of 2006 (theorem_1_1, the introduction on p. 2 of the preprint), which says that the note settled the conjecture of Bollobás, Erdős and Szemerédi, is the claimant's own later account and the source of the transversal form of the result recorded above; it is not independent review. This corpus holds no copy of the note; its abstract is public on the publisher's page, and no step of its proof was checked. The acceptance recorded here rests on the publication and the curator's credit, not on a local review.