{"title":"巴拿赫空间 J 和中的投影","authors":"Manuel González, Javier Pello","doi":"10.1007/s13398-024-01654-4","DOIUrl":null,"url":null,"abstract":"<p>We study some families of projections in the <i>J</i>-sums of Banach spaces <span>\\(J(\\Phi )\\)</span> and <span>\\({\\hat{J}}(\\Phi )\\)</span> introduced by Bellenot. As an application, we show that, under some conditions, <span>\\(J(\\Phi )\\)</span> and <span>\\({\\hat{J}}(\\Phi )\\)</span> are subprojective, i.e., every closed infinite-dimensional subspace of either of them contains a complemented infinite-dimensional subspace.</p>","PeriodicalId":21293,"journal":{"name":"Revista de la Real Academia de Ciencias Exactas, Físicas y Naturales. Serie A. Matemáticas","volume":"211 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Projections in the J-sums of Banach spaces\",\"authors\":\"Manuel González, Javier Pello\",\"doi\":\"10.1007/s13398-024-01654-4\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>We study some families of projections in the <i>J</i>-sums of Banach spaces <span>\\\\(J(\\\\Phi )\\\\)</span> and <span>\\\\({\\\\hat{J}}(\\\\Phi )\\\\)</span> introduced by Bellenot. As an application, we show that, under some conditions, <span>\\\\(J(\\\\Phi )\\\\)</span> and <span>\\\\({\\\\hat{J}}(\\\\Phi )\\\\)</span> are subprojective, i.e., every closed infinite-dimensional subspace of either of them contains a complemented infinite-dimensional subspace.</p>\",\"PeriodicalId\":21293,\"journal\":{\"name\":\"Revista de la Real Academia de Ciencias Exactas, Físicas y Naturales. Serie A. Matemáticas\",\"volume\":\"211 1\",\"pages\":\"\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2024-09-17\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Revista de la Real Academia de Ciencias Exactas, Físicas y Naturales. Serie A. Matemáticas\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1007/s13398-024-01654-4\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Revista de la Real Academia de Ciencias Exactas, Físicas y Naturales. Serie A. Matemáticas","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1007/s13398-024-01654-4","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
We study some families of projections in the J-sums of Banach spaces \(J(\Phi )\) and \({\hat{J}}(\Phi )\) introduced by Bellenot. As an application, we show that, under some conditions, \(J(\Phi )\) and \({\hat{J}}(\Phi )\) are subprojective, i.e., every closed infinite-dimensional subspace of either of them contains a complemented infinite-dimensional subspace.