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arXiv · 2012.07567

Divisibility of Spheres with Measurable Pieces

Clinton T. Conley·Jan Grebík·Oleg Pikhurko
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Abstract

For an $r$-tuple $(\gamma_1,\ldots,\gamma_r)$ of special orthogonal $d\times d$ matrices, we say that the Euclidean $(d-1)$-dimensional sphere $S^{d-1}$ is $(\gamma_1,\ldots,\gamma_r)$-divisible if there is a subset $A\subseteq S^{d-1}$ such that its translations by the rotations $\gamma_1,\ldots,\gamma_r$ partition the sphere. Motivated by some old open questions of Mycielski and Wagon, we investigate the version of this notion where the set $A$ has to be measurable with respect to the spherical measure. Our main result shows that measurable divisibility is impossible for a "generic" (in various meanings) $r$-tuple of rotations. This is in stark contrast to the recent result of Conley, Marks and Unger which implies that, for every "generic" $r$-tuple, divisibility is possible with parts that have the property of Baire.

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Clinton T. Conley, Jan Grebík, Oleg Pikhurko. 2020-12-09. Divisibility of Spheres with Measurable Pieces. https://arxiv.org/abs/2012.07567

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