{"title":"ℓ_1-preduals的显式模型和ℓ_1中的弱*定点性质","authors":"E. Casini, E. Miglierina, Łukasz Piasecki","doi":"10.12775/tmna.2023.009","DOIUrl":null,"url":null,"abstract":"We provide a concrete isometric description of all the preduals of $\\ell_1$ \nfor which the standard basis in $\\ell_1$ has a finite number of $w^*$-limit points.\n Then, we apply this result to give an example of an $\\ell_1$-predual $X$ such\n that its dual $X^*$ lacks the weak$^*$ fixed point property for nonexpansive\n mappings (briefly, $w^*$-FPP), but $X$ does not contain an isometric copy \nof any hyperplane $W_{\\alpha}$ of the space $c$ of convergent sequences such\n that $W_\\alpha$ is a predual of $\\ell_1$ and $W_\\alpha^*$ lacks the $w^*$-FPP.\n This answers a question left open in the 2017 paper of the present authors.","PeriodicalId":0,"journal":{"name":"","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Explicit models of ℓ_1-preduals and the weak* fixed point property in ℓ_1\",\"authors\":\"E. Casini, E. Miglierina, Łukasz Piasecki\",\"doi\":\"10.12775/tmna.2023.009\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"We provide a concrete isometric description of all the preduals of $\\\\ell_1$ \\nfor which the standard basis in $\\\\ell_1$ has a finite number of $w^*$-limit points.\\n Then, we apply this result to give an example of an $\\\\ell_1$-predual $X$ such\\n that its dual $X^*$ lacks the weak$^*$ fixed point property for nonexpansive\\n mappings (briefly, $w^*$-FPP), but $X$ does not contain an isometric copy \\nof any hyperplane $W_{\\\\alpha}$ of the space $c$ of convergent sequences such\\n that $W_\\\\alpha$ is a predual of $\\\\ell_1$ and $W_\\\\alpha^*$ lacks the $w^*$-FPP.\\n This answers a question left open in the 2017 paper of the present authors.\",\"PeriodicalId\":0,\"journal\":{\"name\":\"\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0,\"publicationDate\":\"2024-03-10\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://doi.org/10.12775/tmna.2023.009\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"","FirstCategoryId":"100","ListUrlMain":"https://doi.org/10.12775/tmna.2023.009","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Explicit models of ℓ_1-preduals and the weak* fixed point property in ℓ_1
We provide a concrete isometric description of all the preduals of $\ell_1$
for which the standard basis in $\ell_1$ has a finite number of $w^*$-limit points.
Then, we apply this result to give an example of an $\ell_1$-predual $X$ such
that its dual $X^*$ lacks the weak$^*$ fixed point property for nonexpansive
mappings (briefly, $w^*$-FPP), but $X$ does not contain an isometric copy
of any hyperplane $W_{\alpha}$ of the space $c$ of convergent sequences such
that $W_\alpha$ is a predual of $\ell_1$ and $W_\alpha^*$ lacks the $w^*$-FPP.
This answers a question left open in the 2017 paper of the present authors.