English

Obstacles for splitting multidimensional necklaces

Combinatorics 2016-01-29 v3 General Topology Metric Geometry

Abstract

The well-known "necklace splitting theorem" of Alon asserts that every kk-colored necklace can be fairly split into qq parts using at most tt cuts, provided k(q1)tk(q-1)\leq t. In a joint paper with Alon et al. we studied a kind of opposite question. Namely, for which values of kk and tt there is a measurable kk-coloring of the real line such that no interval has a fair splitting into 22 parts with at most tt cuts? We proved that k>t+2k>t+2 is a sufficient condition (while k>tk>t is necessary). We generalize this result to Euclidean spaces of arbitrary dimension dd, and to arbitrary number of parts qq. We prove that if k(q1)>t+d+q1k(q-1)>t+d+q-1, then there is a measurable kk-coloring of Rd\mathbb{R}^d such that no axis-aligned cube has a fair qq-splitting using at most tt axis-aligned hyperplane cuts. Our bound is of the same order as a necessary condition k(q1)>tk(q-1)>t implied by a theorem of Alon. Moreover for d=1,q=2d=1,q=2 we get exactly the result of of Alon et al. Additionally, we prove that if a stronger inequality k(q1)>dt+d+q1k(q-1)>dt+d+q-1 is satisfied, then there is a measurable kk-coloring of Rd\mathbb{R}^d with no axis-aligned cube having a fair qq-splitting using at most tt arbitrary hyperplane cuts. The proofs are based on the topological Baire category theorem and use algebraic independence over suitably chosen fields.

Keywords

Cite

@article{arxiv.1304.5390,
  title  = {Obstacles for splitting multidimensional necklaces},
  author = {Michał Lasoń},
  journal= {arXiv preprint arXiv:1304.5390},
  year   = {2016}
}

Comments

final version, 14 pages

R2 v1 2026-06-22T00:02:55.745Z