{"title":"沿 IP0 集多项式图像的 Khintchine 型结果的失败","authors":"Rigoberto Zelada","doi":"10.3934/dcds.2023152","DOIUrl":null,"url":null,"abstract":"In\"IP-sets and polynomial recurrence\", Bergelson, Furstenberg, and McCutcheon established the following far reaching extension of Khintchine's recurrence theorem: For any invertible probability preserving system $(X,\\mathcal A,\\mu,T)$, any non-constant polynomial $p\\in\\mathbb Z[x]$ with $p(0)=0$, any $A\\in\\mathcal A$, and any $\\epsilon>0$, the set $$R_\\epsilon^p(A)=\\{n\\in\\mathbb N\\,|\\,\\mu(A\\cap T^{-p(n)}A)>\\mu^2(A)-\\epsilon\\}$$ is IP$^*$, meaning that for any increasing sequence $(n_k)_{k\\in\\mathbb N}$ in $\\mathbb N$, $$\\text{FS}((n_k)_{k\\in\\mathbb N})\\cap R_\\epsilon^p(A)\\neq \\emptyset,$$ where $$\\text{FS}((n_k)_{k\\in\\mathbb N})=\\{\\sum_{j\\in F}n_j\\,|\\,F\\subseteq \\mathbb N\\,\\text{ is finite}\\text{ and }F\\neq\\emptyset\\}=\\{n_{k_1}+\\cdots+n_{k_t}\\,|\\,k_1<\\cdots<k_t,\\,t\\in\\mathbb N\\}.$$ In view of the potential new applications to combinatorics, this result has led to the question of whether a further strengthening of Khintchine's recurrence theorem holds, namely whether the set $R_\\epsilon^p(A)$ is IP$_0^*$ meaning that there exists a $t\\in\\mathbb N$ such that for any finite sequence $n_1<\\cdots<n_t$ in $\\mathbb N$, $$\\{\\sum_{j\\in F}n_j\\,|\\,F\\subseteq \\{1,...,t\\}\\text{ and }F\\neq \\emptyset\\}\\cap R_\\epsilon^p(A)\\neq \\emptyset.$$ In this paper we give a negative answer to this question by showing that for any given polynomial $p\\in\\mathbb Z[x]$ with deg$(p)>1$ and $p(0)=0$ there is an invertible probability preserving system $(X,\\mathcal A,\\mu,T)$, a set $A\\in\\mathcal A$, and an $\\epsilon>0$ for which the set $R_\\epsilon^p(A)$ is not IP$_0^*$.","PeriodicalId":51007,"journal":{"name":"Discrete and Continuous Dynamical Systems","volume":"85 1","pages":""},"PeriodicalIF":1.1000,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Failure of Khintchine-type results along the polynomial image of IP0 sets\",\"authors\":\"Rigoberto Zelada\",\"doi\":\"10.3934/dcds.2023152\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"In\\\"IP-sets and polynomial recurrence\\\", Bergelson, Furstenberg, and McCutcheon established the following far reaching extension of Khintchine's recurrence theorem: For any invertible probability preserving system $(X,\\\\mathcal A,\\\\mu,T)$, any non-constant polynomial $p\\\\in\\\\mathbb Z[x]$ with $p(0)=0$, any $A\\\\in\\\\mathcal A$, and any $\\\\epsilon>0$, the set $$R_\\\\epsilon^p(A)=\\\\{n\\\\in\\\\mathbb N\\\\,|\\\\,\\\\mu(A\\\\cap T^{-p(n)}A)>\\\\mu^2(A)-\\\\epsilon\\\\}$$ is IP$^*$, meaning that for any increasing sequence $(n_k)_{k\\\\in\\\\mathbb N}$ in $\\\\mathbb N$, $$\\\\text{FS}((n_k)_{k\\\\in\\\\mathbb N})\\\\cap R_\\\\epsilon^p(A)\\\\neq \\\\emptyset,$$ where $$\\\\text{FS}((n_k)_{k\\\\in\\\\mathbb N})=\\\\{\\\\sum_{j\\\\in F}n_j\\\\,|\\\\,F\\\\subseteq \\\\mathbb N\\\\,\\\\text{ is finite}\\\\text{ and }F\\\\neq\\\\emptyset\\\\}=\\\\{n_{k_1}+\\\\cdots+n_{k_t}\\\\,|\\\\,k_1<\\\\cdots<k_t,\\\\,t\\\\in\\\\mathbb N\\\\}.$$ In view of the potential new applications to combinatorics, this result has led to the question of whether a further strengthening of Khintchine's recurrence theorem holds, namely whether the set $R_\\\\epsilon^p(A)$ is IP$_0^*$ meaning that there exists a $t\\\\in\\\\mathbb N$ such that for any finite sequence $n_1<\\\\cdots<n_t$ in $\\\\mathbb N$, $$\\\\{\\\\sum_{j\\\\in F}n_j\\\\,|\\\\,F\\\\subseteq \\\\{1,...,t\\\\}\\\\text{ and }F\\\\neq \\\\emptyset\\\\}\\\\cap R_\\\\epsilon^p(A)\\\\neq \\\\emptyset.$$ In this paper we give a negative answer to this question by showing that for any given polynomial $p\\\\in\\\\mathbb Z[x]$ with deg$(p)>1$ and $p(0)=0$ there is an invertible probability preserving system $(X,\\\\mathcal A,\\\\mu,T)$, a set $A\\\\in\\\\mathcal A$, and an $\\\\epsilon>0$ for which the set $R_\\\\epsilon^p(A)$ is not IP$_0^*$.\",\"PeriodicalId\":51007,\"journal\":{\"name\":\"Discrete and Continuous Dynamical Systems\",\"volume\":\"85 1\",\"pages\":\"\"},\"PeriodicalIF\":1.1000,\"publicationDate\":\"2023-07-17\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Discrete and Continuous Dynamical Systems\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://doi.org/10.3934/dcds.2023152\",\"RegionNum\":3,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Discrete and Continuous Dynamical Systems","FirstCategoryId":"100","ListUrlMain":"https://doi.org/10.3934/dcds.2023152","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATHEMATICS","Score":null,"Total":0}
Failure of Khintchine-type results along the polynomial image of IP0 sets
In"IP-sets and polynomial recurrence", Bergelson, Furstenberg, and McCutcheon established the following far reaching extension of Khintchine's recurrence theorem: For any invertible probability preserving system $(X,\mathcal A,\mu,T)$, any non-constant polynomial $p\in\mathbb Z[x]$ with $p(0)=0$, any $A\in\mathcal A$, and any $\epsilon>0$, the set $$R_\epsilon^p(A)=\{n\in\mathbb N\,|\,\mu(A\cap T^{-p(n)}A)>\mu^2(A)-\epsilon\}$$ is IP$^*$, meaning that for any increasing sequence $(n_k)_{k\in\mathbb N}$ in $\mathbb N$, $$\text{FS}((n_k)_{k\in\mathbb N})\cap R_\epsilon^p(A)\neq \emptyset,$$ where $$\text{FS}((n_k)_{k\in\mathbb N})=\{\sum_{j\in F}n_j\,|\,F\subseteq \mathbb N\,\text{ is finite}\text{ and }F\neq\emptyset\}=\{n_{k_1}+\cdots+n_{k_t}\,|\,k_1<\cdots1$ and $p(0)=0$ there is an invertible probability preserving system $(X,\mathcal A,\mu,T)$, a set $A\in\mathcal A$, and an $\epsilon>0$ for which the set $R_\epsilon^p(A)$ is not IP$_0^*$.
期刊介绍:
DCDS, series A includes peer-reviewed original papers and invited expository papers on the theory and methods of analysis, differential equations and dynamical systems. This journal is committed to recording important new results in its field and maintains the highest standards of innovation and quality. To be published in this journal, an original paper must be correct, new, nontrivial and of interest to a substantial number of readers.