{"title":"$c_0$的改造与最小位移问题","authors":"Łukasz Piasecki","doi":"10.1515/UMCSMATH-2015-0008","DOIUrl":null,"url":null,"abstract":"The aim of this paper is to show that for every Banach space \\((X, \\|\\cdot\\|)\\) containing asymptotically isometric copy of the space \\(c_0\\) there is a bounded, closed and convex set \\(C \\subset X\\) with the Chebyshev radius \\(r(C) = 1\\) such that for every \\(k \\geq 1 \\) there exists a \\(k\\)-contractive mapping \\(T : C \\to C\\) with \\(\\| x - Tx \\| > 1 − 1/k\\) for any \\(x \\in C\\).","PeriodicalId":340819,"journal":{"name":"Annales Umcs, Mathematica","volume":"7 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Renormings of $c_0$ and the minimal displacement problem\",\"authors\":\"Łukasz Piasecki\",\"doi\":\"10.1515/UMCSMATH-2015-0008\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"The aim of this paper is to show that for every Banach space \\\\((X, \\\\|\\\\cdot\\\\|)\\\\) containing asymptotically isometric copy of the space \\\\(c_0\\\\) there is a bounded, closed and convex set \\\\(C \\\\subset X\\\\) with the Chebyshev radius \\\\(r(C) = 1\\\\) such that for every \\\\(k \\\\geq 1 \\\\) there exists a \\\\(k\\\\)-contractive mapping \\\\(T : C \\\\to C\\\\) with \\\\(\\\\| x - Tx \\\\| > 1 − 1/k\\\\) for any \\\\(x \\\\in C\\\\).\",\"PeriodicalId\":340819,\"journal\":{\"name\":\"Annales Umcs, Mathematica\",\"volume\":\"7 1\",\"pages\":\"0\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2014-12-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Annales Umcs, Mathematica\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1515/UMCSMATH-2015-0008\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Annales Umcs, Mathematica","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1515/UMCSMATH-2015-0008","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Renormings of $c_0$ and the minimal displacement problem
The aim of this paper is to show that for every Banach space \((X, \|\cdot\|)\) containing asymptotically isometric copy of the space \(c_0\) there is a bounded, closed and convex set \(C \subset X\) with the Chebyshev radius \(r(C) = 1\) such that for every \(k \geq 1 \) there exists a \(k\)-contractive mapping \(T : C \to C\) with \(\| x - Tx \| > 1 − 1/k\) for any \(x \in C\).