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arXiv · 2309.05764

Equality cases of the Alexandrov--Fenchel inequality are not in the polynomial hierarchy

Swee Hong Chan·Igor Pak
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Abstract

Describing the equality conditions of the Alexandrov--Fenchel inequality has been a major open problem for decades. We prove that in the case of convex polytopes, this description is not in the polynomial hierarchy unless the polynomial hierarchy collapses to a finite level. This is the first hardness result for the problem, and is a complexity counterpart of the recent result by Shenfeld and van Handel (arXiv:archive/201104059), which gave a geometric characterization of the equality conditions. The proof involves Stanley's order polytopes and employs poset theoretic technology.

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BibTeXRIS

Swee Hong Chan, Igor Pak. 2023-09-11. Equality cases of the Alexandrov--Fenchel inequality are not in the polynomial hierarchy. https://doi.org/10.1017/fmp.2024.20

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