A Szemerédi-type regularity lemma in abelian groups, with applications
A Szemerédi-type regularity lemma in abelian groups, with applications
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阿贝尔群中的 Szemerédi 型正则引理及其应用
DOI:
10.1007/s00039-005-0509-8
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发表时间:
2003
期刊:
影响因子:
--
通讯作者:
B. Green
中科院分区:
文献类型:
--
作者:
B. Green
Abstract.Szemerédi’s regularity lemma is an important tool in graph theory which has applications throughout combinatorics. In this paper we prove an analogue of Szemerédi’s regularity lemma in the context of abelian groups and use it to derive some results in additive number theory. One is a structure theorem for sets which are almost sum-free. If
$$A \subseteq \{1,\ldots,N\}$$ has δ N2 triples (a1, a2, a3) for which a1 + a2 = a3 then A = B ∪ C, where B is sum-free and |C| = δ′N, and
$$\delta^{\prime} \rightarrow 0$$ as
$$\delta \rightarrow 0.$$ Another answers a question of Bergelson, Host and Kra. If
$$\alpha, \epsilon > 0,$$ if
$$N\,>\,N_{0}(\alpha, \epsilon)$$ and if
$$A \subseteq \{1,\ldots,N\}$$ has size α N, then there is some d ≠ 0 such that A contains at least
$$(\alpha^{3}-\epsilon)N$$ three-term arithmetic progressions with common difference d.