Conjecture on dense colorings for typical norms

From papers

For a norm \|\cdot\| on Rn\mathbb{R}^n, write χ(Rn;)\chi(\mathbb{R}^n;\|\cdot\|) for the chromatic number of its unit-distance graph, and let χed(Rn;)\chi_{ed}(\mathbb{R}^n;\|\cdot\|) denote the least number of color classes in a proper coloring whose classes are dense in Rn\mathbb{R}^n. A norm is called typical if it belongs to the Baire-category typical set in the space of norms.

Typical-norm dense-coloring conjecture. For a typical norm,

χed(Rn;)=χ(Rn;)=2n.\chi_{ed}\bigl(\mathbb{R}^n;\|\cdot\|\bigr)=\chi\bigl(\mathbb{R}^n;\|\cdot\|\bigr)=2^n.

For typical norms, the equality χ(Rn;)=2n\chi(\mathbb{R}^n;\|\cdot\|)=2^n is known, but the coloring establishing it is nonconstructive. The conjecture asserts that requiring every color class to be dense does not increase the chromatic number.

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Sources & referencesView supporting material

Primary source

Maxim Didin and Vsevolod Voronov, “The chromatic number of Euclidean space with dense color classes”, arXiv:2607.19946 (2026).

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