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arXiv 2303.01969math.MG
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具有受控增长的覆盖的渐近维数

Asymptotic dimension for covers with controlled growth

David Hume, John M. Mackay, Romain Tessera

AI总结:

本文引入允许受控增长无界覆盖的渐近维数推广,并据此证明双曲空间、正则树幂及自由群之间若干正则映射、粗嵌入与拟等距嵌入的不存在性。

摘要:

我们证明了在通常研究的空间之间存在正则映射(或粗嵌入)的若干障碍。例如,当 n≥3 时,不存在正则映射(或粗嵌入) ℍⁿ→ℍⁿ⁻¹×Y;而只要 Y 是具有次指数增长的有界度图,其中 T₃ 是 3-正则树,也不存在 (T₃)ⁿ→(T₃)ⁿ⁻¹×Y。我们还解决了 Benjamini–Schramm–Timár 的一个问题,证明了当 Y 是至多具有多项式增长的有界度图时,不存在正则映射 ℍ²→T₃×Y;而当 Y 具有次指数增长时,不存在拟等距嵌入。最后,我们证明不存在正则映射 Fⁿ→ℤ≀Fⁿ⁻¹,其中 F 是二生成元自由群。为证明这些结果,我们引入并研究渐近维数的推广,其允许具有受控增长的无界覆盖。对于有界度图,这些不变量关于正则映射(因而关于粗嵌入)是单调的。

英文摘要:

We prove various obstructions to the existence of regular maps (or coarse embeddings) between commonly studied spaces. For instance, there is no regular map (or coarse embedding) $\mathbb H^n\to\mathbb H^{n-1}\times Y$ for $n\geq 3$, or $(T_3)^n \to (T_3)^{n-1}\times Y$ whenever $Y$ is a bounded degree graph with subexponential growth, where $T_3$ is the $3$-regular tree. We also resolve a question of Benjamini-Schramm-Timár, proving that there is no regular map $\mathbb H^2 \to T_3 \times Y$ whenever $Y$ is a bounded degree graph with at most polynomial growth, and no quasi-isometric embedding whenever $Y$ has subexponential growth. Finally, we show that there is no regular map $F^n\to \mathbb Z\wr F^{n-1}$ where $F$ is the free group on two generators. To prove these results, we introduce and study generalizations of asymptotic dimension which allow unbounded covers with controlled growth. For bounded degree graphs, these invariants are monotone with respect to regular maps (hence coarse embeddings).

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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