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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. As the zbMATH review Zbl 0624.05028 (A. Tucker) states the paper's results: if GG is a nonempty graph in which every vertex set SS with at most 2n−22n-2 vertices has ∣N(S)∣≥(d+1)∣S∣|N(S)|\ge(d+1)|S|, where N(S)N(S) is the set of neighbors of SS, then GG contains every tree with nn vertices and maximum degree at most dd; and for fixed dd and any real 0<s<10<s<1, for every nn there is a graph with O(n)O(n) edges every subgraph of which with a fraction ss of its edges contains every tree with nn vertices and maximum degree at most dd. Taking s=12s=\frac12, one color class of any 22-coloring of that graph's edges has at least half its edges, so r^(T)=Od(n)\hat r(T)=O_d(n) for every such tree TT (an elementary step of this corpus). Draganić and Petrova (2025, p. 2) quote the result in this form: "for every tree TT of bounded degree on nn vertices, r^(T)=O(n)\hat r(T)=O(n)".

Covers. The statement of Problem 559 for trees of maximum degree at most dd, for every dd; paths are the case d=2d=2. Not covered: graphs with cycles. The statement fails in general at maximum degree three (the pages Rödl and Szemerédi 2000 and Tikhomirov 2022).

Dating. The page is dated by the issue month of the journal record (Combinatorica 7 (1987), no. 1, March 1987, per the Crossref record); the day in the page name is a placeholder.

Acceptance. Refereed: Expanding graphs contain all small trees, Combinatorica 7 (1987), no. 1, 71--76. The site's curator, T. F. Bloom, credits the tree case to this paper in the problem's commentary, but the DISPROVED label settles the problem in the negative and credits no positive sub-claim, so the credit is not reviewed evidence.

Read depth. The paper is not held here; the statement is taken from the zbMATH review and agrees with the quotation of Draganić and Petrova. No proof is covered, and nothing is independently reviewed in this corpus.

Depends on. Nothing in this wiki; the result is the paper's own theorem.