The cylindrical width of transitive sets
@inproceedings{Sah2021TheCW, title={The cylindrical width of transitive sets}, author={Ashwin Sah and Mehtaab Sawhney and Yufei Zhao}, year={2021} }
The following counterintuitive fact was conjectured by the third author and proved by Green [4]. It says that every finite transitive subset of a high dimensional sphere is close to some hyperplane. Here a subset X of a sphere in Rd is transitive if for every x, x′ ∈ X, there is some g ∈ O(Rd) so that gX = X and gx = x′. We say that X has width at most 2r if it lies within distance r of some hyperplane. The finiteness assumption is important since otherwise the whole sphere is a counterexample.
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