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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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Source: original paper, printed pp. 529–530.

Write Rn→(A,B)\mathbb R^n\to(A,B) when every red-blue coloring of the whole space has a red congruent copy of AA or a blue congruent copy of BB. A congruent copy is an image under a Euclidean isometry. A translate B+tB+t is more restrictive: it preserves the given orientation. No measurability or other regularity of a coloring is assumed.

Let ℓj={0,e,…,(j−1)e}\ell_j=\{0,e,\ldots,(j-1)e\}, where ∣e∣=1|e|=1. It contains jj points and j−1j-1 unit gaps. A kk-dimensional brick with positive side lengths d1,…,dkd_1,\ldots,d_k means its 2k2^k vertices, isometric to ∏i=1k{0,di}\prod_{i=1}^k\{0,d_i\}.

The source calls a finite configuration Ramsey when for every finite color count it is forced in some sufficiently high dimension. This is a statement about dimension as well as color count. A planar conclusion, a higher-dimensional conclusion and a translation-only conclusion must not be interchanged.

The paper's open questions describe its historical state. In particular its comments about five blue collinear points or a blue unit square in the plane do not establish the current status of Problem 188 or Problem 214.