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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. In the reading α=ωβ\alpha=\omega^\beta of Problem 592 (its Formulation), Specker answers the question at every finite exponent β≥2\beta\ge2. He proves ω2→(ω2,n)2\omega^2\to(\omega^2,n)^2 for every finite nn, so β=2\beta=2 has the property, and ω3↛(ω3,3)2\omega^3\not\to(\omega^3,3)^2. He introduces pinning maps (a map from α\alpha into β\beta sending every subset of order type α\alpha to a set of order type β\beta), observes that a partition relation α→(α,χ)2\alpha\to(\alpha,\chi)^2 passes to every β\beta to which α\alpha can be pinned, and shows that ωm\omega^m can be pinned to ω3\omega^3 for 3≤m<ω3\le m<\omega. Together these give ωm↛(ωm,3)2\omega^m\not\to(\omega^m,3)^2 for every finite m≥3m\ge3, so no finite β≥3\beta\ge3 has the property. The paper is E. Specker, Teilmengen von Mengen mit Relationen, Comment. Math. Helv. 31 (1956/57), 302--314, DOI 10.1007/BF02564361, the site's [Sp57]; the publisher's record gives receipt on 8 October 1956 and the issue date December 1956, and the page name carries the first day of that month, since the record gives no day. The paper is not filed in the library: the statements above follow the account of it in the introduction of Galvin and Larson's Pinning countable ordinals (card) and in Schipperus's history on p. 1196 of Countable partition ordinals (card), not the paper's pages.

Covers. The exponents β=2\beta=2 (the property holds) and every finite β≥3\beta\ge3 (it fails). Not covered: every infinite β\beta, among them Chang's β=ω\beta=\omega.

Depends on. No page of this wiki.

Acceptance. Refereed: the paper appeared in Commentarii Mathematici Helvetici, volume 31. The site labels the problem OPEN, and its commentary crediting Specker on an open problem is not an acceptance, so no reviewed evidence is listed.