{"title":"分段范畴与不动点性质","authors":"C. A. I. Zapata, Jes'us Gonz'alez","doi":"10.12775/tmna.2020.033","DOIUrl":null,"url":null,"abstract":"In this work we exhibit an unexpected connection between sectional category theory and the fixed point property. On the one hand, a topological space $X$ is said to have \\textit{the fixed point property} (FPP) if, for every continuous self-map $f$ of $X$, there is a point $x$ of $X$ such that $f(x)=x$. On the other hand, for a continuous surjection $p:E\\to B$, the \\textit{standard sectional number} $sec_{\\text{op}}(p)$ is the minimal cardinality of open covers $\\{U_i\\}$ of $B$ such that each $U_i$ admits a continuous local section for $p$. Let $F(X,k)$ denote the configuration space of $k$ ordered distinct points in $X$ and consider the natural projection $\\pi_{k,1}:F(X,k)\\to X$. We demonstrate that a space $X$ has the FPP if and only if $sec_{\\text{op}}(\\pi_{2,1})=2$. This characterization connects a standard problem in fixed point theory to current research trends in topological robotics.","PeriodicalId":8433,"journal":{"name":"arXiv: Algebraic Topology","volume":"24 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2019-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"3","resultStr":"{\"title\":\"Sectional category and the fixed point property\",\"authors\":\"C. A. I. Zapata, Jes'us Gonz'alez\",\"doi\":\"10.12775/tmna.2020.033\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"In this work we exhibit an unexpected connection between sectional category theory and the fixed point property. On the one hand, a topological space $X$ is said to have \\\\textit{the fixed point property} (FPP) if, for every continuous self-map $f$ of $X$, there is a point $x$ of $X$ such that $f(x)=x$. On the other hand, for a continuous surjection $p:E\\\\to B$, the \\\\textit{standard sectional number} $sec_{\\\\text{op}}(p)$ is the minimal cardinality of open covers $\\\\{U_i\\\\}$ of $B$ such that each $U_i$ admits a continuous local section for $p$. Let $F(X,k)$ denote the configuration space of $k$ ordered distinct points in $X$ and consider the natural projection $\\\\pi_{k,1}:F(X,k)\\\\to X$. We demonstrate that a space $X$ has the FPP if and only if $sec_{\\\\text{op}}(\\\\pi_{2,1})=2$. This characterization connects a standard problem in fixed point theory to current research trends in topological robotics.\",\"PeriodicalId\":8433,\"journal\":{\"name\":\"arXiv: Algebraic Topology\",\"volume\":\"24 1\",\"pages\":\"\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2019-12-07\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"3\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"arXiv: Algebraic Topology\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.12775/tmna.2020.033\",\"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: Algebraic Topology","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.12775/tmna.2020.033","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
In this work we exhibit an unexpected connection between sectional category theory and the fixed point property. On the one hand, a topological space $X$ is said to have \textit{the fixed point property} (FPP) if, for every continuous self-map $f$ of $X$, there is a point $x$ of $X$ such that $f(x)=x$. On the other hand, for a continuous surjection $p:E\to B$, the \textit{standard sectional number} $sec_{\text{op}}(p)$ is the minimal cardinality of open covers $\{U_i\}$ of $B$ such that each $U_i$ admits a continuous local section for $p$. Let $F(X,k)$ denote the configuration space of $k$ ordered distinct points in $X$ and consider the natural projection $\pi_{k,1}:F(X,k)\to X$. We demonstrate that a space $X$ has the FPP if and only if $sec_{\text{op}}(\pi_{2,1})=2$. This characterization connects a standard problem in fixed point theory to current research trends in topological robotics.