{"title":"随机多项式单位圆附近的实根","authors":"Marcus Michelen","doi":"10.1090/TRAN/8379","DOIUrl":null,"url":null,"abstract":"Let $f_n(z) = \\sum_{k = 0}^n \\varepsilon_k z^k$ be a random polynomial where $\\varepsilon_0,\\ldots,\\varepsilon_n$ are i.i.d. random variables with $\\mathbb{E} \\varepsilon_1 = 0$ and $\\mathbb{E} \\varepsilon_1^2 = 1$. Letting $r_1, r_2,\\ldots, r_k$ denote the real roots of $f_n$, we show that the point process defined by $\\{|r_1| - 1,\\ldots, |r_k| - 1 \\}$ converges to a non-Poissonian limit on the scale of $n^{-1}$ as $n \\to \\infty$. Further, we show that for each $\\delta > 0$, $f_n$ has a real root within $\\Theta_{\\delta}(1/n)$ of the unit circle with probability at least $1 - \\delta$. This resolves a conjecture of Shepp and Vanderbei from 1995 by confirming its weakest form and refuting its strongest form.","PeriodicalId":8470,"journal":{"name":"arXiv: Probability","volume":"55 33 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2020-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"3","resultStr":"{\"title\":\"Real roots near the unit circle of random polynomials\",\"authors\":\"Marcus Michelen\",\"doi\":\"10.1090/TRAN/8379\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Let $f_n(z) = \\\\sum_{k = 0}^n \\\\varepsilon_k z^k$ be a random polynomial where $\\\\varepsilon_0,\\\\ldots,\\\\varepsilon_n$ are i.i.d. random variables with $\\\\mathbb{E} \\\\varepsilon_1 = 0$ and $\\\\mathbb{E} \\\\varepsilon_1^2 = 1$. Letting $r_1, r_2,\\\\ldots, r_k$ denote the real roots of $f_n$, we show that the point process defined by $\\\\{|r_1| - 1,\\\\ldots, |r_k| - 1 \\\\}$ converges to a non-Poissonian limit on the scale of $n^{-1}$ as $n \\\\to \\\\infty$. Further, we show that for each $\\\\delta > 0$, $f_n$ has a real root within $\\\\Theta_{\\\\delta}(1/n)$ of the unit circle with probability at least $1 - \\\\delta$. This resolves a conjecture of Shepp and Vanderbei from 1995 by confirming its weakest form and refuting its strongest form.\",\"PeriodicalId\":8470,\"journal\":{\"name\":\"arXiv: Probability\",\"volume\":\"55 33 1\",\"pages\":\"\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2020-10-21\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"3\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"arXiv: Probability\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1090/TRAN/8379\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv: Probability","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1090/TRAN/8379","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Real roots near the unit circle of random polynomials
Let $f_n(z) = \sum_{k = 0}^n \varepsilon_k z^k$ be a random polynomial where $\varepsilon_0,\ldots,\varepsilon_n$ are i.i.d. random variables with $\mathbb{E} \varepsilon_1 = 0$ and $\mathbb{E} \varepsilon_1^2 = 1$. Letting $r_1, r_2,\ldots, r_k$ denote the real roots of $f_n$, we show that the point process defined by $\{|r_1| - 1,\ldots, |r_k| - 1 \}$ converges to a non-Poissonian limit on the scale of $n^{-1}$ as $n \to \infty$. Further, we show that for each $\delta > 0$, $f_n$ has a real root within $\Theta_{\delta}(1/n)$ of the unit circle with probability at least $1 - \delta$. This resolves a conjecture of Shepp and Vanderbei from 1995 by confirming its weakest form and refuting its strongest form.