{"title":"Ball generated property of direct sums of Banach spaces","authors":"Jan-David Hardtke","doi":"10.3318/PRIA.2015.115.13","DOIUrl":null,"url":null,"abstract":"A Banach space $X$ is said to have the ball generated property (BGP) if every closed, bounded, convex subset of $X$ can be written as an intersection of finite unions of closed balls. In 2002 S. Basu proved that the BGP is stable under (infinite) $c_0$- and $\\ell^p$-sums for $1<p<\\infty$. We will show here that for any absolute, normalised norm $\\|\\cdot\\|_E$ on $\\mathbb{R}^2$ satisfying a certain smoothness condition the direct sum $X\\oplus_E Y$ of two Banach spaces $X$ and $Y$ with respect to $\\|\\cdot\\|_E$ enjoys the BGP whenever $X$ and $Y$ have the BGP.","PeriodicalId":434988,"journal":{"name":"Mathematical Proceedings of the Royal Irish Academy","volume":"52 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"2015-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Mathematical Proceedings of the Royal Irish Academy","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3318/PRIA.2015.115.13","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 1
Abstract
A Banach space $X$ is said to have the ball generated property (BGP) if every closed, bounded, convex subset of $X$ can be written as an intersection of finite unions of closed balls. In 2002 S. Basu proved that the BGP is stable under (infinite) $c_0$- and $\ell^p$-sums for $1