The majorization characterization conjecture for ordinal spaces embeddable in the line

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Let (X,δ)(X,\delta) be an ordinal space with ∣X∣=n∈N+|X|=n\in\mathbb N^+, and let x1,x2,…,xnx_1,x_2,\ldots,x_n be an enumeration of its points satisfying the majorization property. Write X↪R1X\hookrightarrow\mathbb R^1 for embeddability of XX in the real line. Majorization characterization conjecture. If such an enumeration exists, then

X↪R1.X\hookrightarrow\mathbb R^1.

The paper proves that line embeddability implies the existence of an enumeration with the majorization property and states sufficiency for n⩽4n\leqslant4, while explicitly saying that it cannot determine whether sufficiency holds for n>5n>5; the general assertion is therefore open.

References

Primary source

Karsten Keller and Evgeniy Petrov, “Ordinal spaces”, arXiv:2412.17391 (2024).

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