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arXiv 1002.2210math.NTmath.CO
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$\mathbb{Z}_N$上函数的线性型和二次一致性

Linear forms and quadratic uniformity for functions on $\mathbb{Z}_N$

W. T. Gowers, J. Wolf

摘要:

加法组合学中一个非常有用的事实是,可以用来计算阿贝尔群子集中各种结构的数量的解析表达式在拟随机扰动下是稳健的,而且,拟随机性通常可以通过某些容易描述的范数(称为一致性范数)来测量。然而,确定哪种统一性规范适用于哪种结构,却是一个令人惊讶的难题。在[GW09 a]和[GW09 b,GW09 c]中,我们对$G=\mathbb{F}_p^n$形式的群给出了这个问题的完整答案,条件是$p$不太小。在$\mathbb{Z}_N$,大量额外的困难出现,其中最重要的是,“逆定理”,甚至为均匀性规范$\|.\|_{U^3}$需要一个更复杂的(本地)制定。当$N$是素数时,$\mathbb{Z}_N$的子群并不丰富,因此必须使用正则玻尔邻域。本文证明了[GW 09a]中主要猜想的第一个非平凡情形。

英文摘要:

A very useful fact in additive combinatorics is that analytic expressions that can be used to count the number of structures of various kinds in subsets of Abelian groups are robust under quasirandom perturbations, and moreover that quasirandomness can often be measured by means of certain easily described norms, known as uniformity norms. However, determining which uniformity norms work for which structures turns out to be a surprisingly hard question. In [GW09a] and [GW09b, GW09c] we gave a complete answer to this question for groups of the form $G=\mathbb{F}_p^n$, provided $p$ is not too small. In $\mathbb{Z}_N$, substantial extra difficulties arise, of which the most important is that an "inverse theorem" even for the uniformity norm $\|.\|_{U^3}$ requires a more sophisticated (local) formulation. When $N$ is prime, $\mathbb{Z}_N$ is not rich in subgroups, so one must use regular Bohr neighbourhoods instead. In this paper, we prove the first non-trivial case of the main conjecture from [GW09a].

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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