On the number of defects in optimal quantizers on closed surfaces: the hexagonal torus

Fuente: arXiv
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Main Authors: Tisdell, Jack Edward, Choksi, Rustum, Lu, Xin Yang
Format: Preprint
Published: 2025
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author Tisdell, Jack Edward
Choksi, Rustum
Lu, Xin Yang
author_facet Tisdell, Jack Edward
Choksi, Rustum
Lu, Xin Yang
contents We present a strategy for proving an asymptotic upper bound on the number of defects (non-hexagonal Voronoi cells) in the $n$ generator optimal quantizer on a closed surface (i.e., compact 2-manifold without boundary). The program is based upon a general lower bound on the optimal quantization error and related upper bounds for the Löschian numbers $n$ (the norms of the Eisenstein integers) arising from the Goldberg-Coxeter construction. A gap lemma is used to reduce the asymptotics of the number of defects to precisely the asymptotics for the gaps between Löschian numbers. We apply this strategy on the hexagonal torus and prove that the number of defects is at most $O(n^{1/4})$ -- strictly fewer than surfaces with boundary -- and conjecture (based upon the number-theoretic Löschian gap conjecture) that it is in fact $O(\log n)$. Incidentally, the method also yields a related upper bound on the variance of the areas of the Voronoi cells. We show further that the bound on the number of defects holds in a neighborhood of the optimizers. Finally, we remark on the remaining issues for implementation on the 2-sphere.
format Preprint
id arxiv_https___arxiv_org_abs_2503_22680
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the number of defects in optimal quantizers on closed surfaces: the hexagonal torus
Tisdell, Jack Edward
Choksi, Rustum
Lu, Xin Yang
Metric Geometry
Optimization and Control
We present a strategy for proving an asymptotic upper bound on the number of defects (non-hexagonal Voronoi cells) in the $n$ generator optimal quantizer on a closed surface (i.e., compact 2-manifold without boundary). The program is based upon a general lower bound on the optimal quantization error and related upper bounds for the Löschian numbers $n$ (the norms of the Eisenstein integers) arising from the Goldberg-Coxeter construction. A gap lemma is used to reduce the asymptotics of the number of defects to precisely the asymptotics for the gaps between Löschian numbers. We apply this strategy on the hexagonal torus and prove that the number of defects is at most $O(n^{1/4})$ -- strictly fewer than surfaces with boundary -- and conjecture (based upon the number-theoretic Löschian gap conjecture) that it is in fact $O(\log n)$. Incidentally, the method also yields a related upper bound on the variance of the areas of the Voronoi cells. We show further that the bound on the number of defects holds in a neighborhood of the optimizers. Finally, we remark on the remaining issues for implementation on the 2-sphere.
title On the number of defects in optimal quantizers on closed surfaces: the hexagonal torus
topic Metric Geometry
Optimization and Control
url https://arxiv.org/abs/2503.22680