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 second question of Problem 1174 asks for a graph with no such that every coloring of its edges with countably many colors has a monochromatic . The paper's Theorem 2 states: if the existence of a proper class of measurable cardinals is consistent, then it is consistent that for every graph and cardinal there is a graph such that every coloring of the edges of with colors has an induced monochromatic copy of , and implies for every . Theorem 1 is the single step: if , is a graph on and is measurable, a -closed partial order of size adds such an ; Theorem 2 iterates it along a class of measurables, and the paper remarks that the measurable cardinals can be eliminated by §§3--4 of Shelah's 1989 chapter. The introduction names the question whether a graph with and may exist as an old question of Erdős and Hajnal and says the paper solves it, at least consistently. With and the theorem gives a graph with no , since , every countable edge coloring of which has a monochromatic . So ZFC does not refute the existence of such a graph, relative to the consistency of the large cardinals used: the second question is not disprovable in the site's sense.
Covers. The second question of Problem 1174 (the part
k_aleph1_free_graph), as a consistency statement relative to a proper class
of measurable cardinals, or to ZFC alone if the paper's remark on eliminating
them is taken at its word; this page does not check that remark. It settles
one side of that part only: ZFC does not refute the existence of such a graph,
but whether ZFC can prove it is not settled, and one side alone leaves the
question open. It does not cover the first question, which is
Shelah's 1989 result,
nor the question whether such a graph exists in ZFC: Komjáth's 2025 survey
(Problems 52 and 53) records the consistency only, asks for such a graph of
size , and notes that no graph of size at most
can have the property.
Source. P. Komjáth and S. Shelah, A consistent edge partition theorem for infinite graphs, Acta Mathematica Hungarica 61 (1993), no. 1--2, 115--120; DOI 10.1007/BF01872104; MR 1200965; Shelah archive Sh:414; received 2 August 1990, revised January 1991. The paper is not held; this page rests on the introduction and Theorems 1 and 2 in the archive's scan of the printed article, and the proofs were not followed. Komjáth's 2025 survey cites it as its reference [106] and states the theorem in its Problem 53 commentary (source card). The publisher's record dates the issue, volume 61, numbers 1--2, to March 1993 and carries no day, so this page is dated the first of that month.
Acceptance. Refereed: a journal paper in Acta Mathematica Hungarica. Reviewed: the curator of erdosproblems.com, T. F. Bloom, labels the problem not disprovable, and the page's remark credits Shelah with the consistency of a graph with either property without citing a paper; the written source of the second property found is this joint paper, whose introduction claims it, and the thread comment of 9 February 2026 links the archive's copy. The community database records the label from 19 March 2026. Nothing on this page is independently reviewed by this project.
Depends on. No other wiki page; the claim rests on the paper above.