良回归集是分划正则的
Sets of nice recurrence are partition regular
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中文总结 AI 辅助
该研究证明良回归集具有分划正则性,即其任意有限着色均包含单色良回归集,解决了Bergelson的长期问题。
中文摘要 AI 辅助
正整数集R被称为良回归集,当且仅当对任意保测系统(X,μ,T)、所有可测集A⊆X及任意ε>0,存在n∈R使得μ(A∩T⁻ⁿA)≥μ(A)²−ε。我们回答了Bergelson的一个长期问题,证明良回归集具有如下拉姆齐性质:任意良回归集的有限着色都包含一个单色良回归集。
英文摘要
A set of positive integers $R$ is called a set of nice recurrence if for any measure preserving system $(X,μ,T)$, for all measurable $A\subseteq X$, and each $\varepsilon>0$, there exists $n\in R$ such that $μ(A\cap T^{-n}A)\geqslant μ(A)^2 - \varepsilon$. Answering a long-standing question of Bergelson, we show that sets of nice recurrence have the following Ramsey property: any finite colouring of a set of nice recurrence admits a monochromatic set of nice recurrence.