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arXiv · 2309.14539

Colorful Borsuk--Ulam theorems and applications

Florian Frick·Zoe Wellner
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Abstract

We prove a colorful generalization of the Borsuk--Ulam theorem and derive colorful consequences from it, such as a colorful generalization of the ham sandwich theorem. Even in the uncolored case this specializes to a strengthening of the ham sandwich theorem, which given an additional condition, contains a result of Bárány, Hubard, and Jerónimo on well-separated measures as a special case. We prove a colorful generalization of Fan's antipodal sphere covering theorem, we derive a short proof of Gale's colorful KKM theorem, and we prove a colorful generalization of Brouwer's fixed point theorem. Our results also provide an alternative between Radon-type intersection results and KKM-type covering results. Finally, we prove colorful Borsuk--Ulam theorems for higher symmetry.

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Florian Frick, Zoe Wellner. 2023-09-25. Colorful Borsuk--Ulam theorems and applications. https://arxiv.org/abs/2309.14539

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