{"title":"关于极值非展开映射","authors":"Christian Bargetz, Michael Dymond, Katriin Pirk","doi":"arxiv-2409.04292","DOIUrl":null,"url":null,"abstract":"We study the extremality of nonexpansive mappings on a nonempty bounded\nclosed and convex subset of a normed space (therein specific Banach spaces). We\nshow that surjective isometries are extremal in this sense for many Banach\nspaces, including Banach spaces with the Radon-Nikodym property and all\n$C(K)$-spaces for compact Hausdorff $K.$ We also conclude that the typical, in\nthe sense of Baire category, nonexpansive mapping is close to being extremal.","PeriodicalId":501036,"journal":{"name":"arXiv - MATH - Functional Analysis","volume":"73 1 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"On extremal nonexpansive mappings\",\"authors\":\"Christian Bargetz, Michael Dymond, Katriin Pirk\",\"doi\":\"arxiv-2409.04292\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"We study the extremality of nonexpansive mappings on a nonempty bounded\\nclosed and convex subset of a normed space (therein specific Banach spaces). We\\nshow that surjective isometries are extremal in this sense for many Banach\\nspaces, including Banach spaces with the Radon-Nikodym property and all\\n$C(K)$-spaces for compact Hausdorff $K.$ We also conclude that the typical, in\\nthe sense of Baire category, nonexpansive mapping is close to being extremal.\",\"PeriodicalId\":501036,\"journal\":{\"name\":\"arXiv - MATH - Functional Analysis\",\"volume\":\"73 1 1\",\"pages\":\"\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2024-09-06\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"arXiv - MATH - Functional Analysis\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/arxiv-2409.04292\",\"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 - MATH - Functional Analysis","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2409.04292","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
We study the extremality of nonexpansive mappings on a nonempty bounded
closed and convex subset of a normed space (therein specific Banach spaces). We
show that surjective isometries are extremal in this sense for many Banach
spaces, including Banach spaces with the Radon-Nikodym property and all
$C(K)$-spaces for compact Hausdorff $K.$ We also conclude that the typical, in
the sense of Baire category, nonexpansive mapping is close to being extremal.