{"title":"将某些向量值函数空间表示为张量积","authors":"M. Abtahi","doi":"10.1007/s10476-023-0218-2","DOIUrl":null,"url":null,"abstract":"<div><p>Let <i>E</i> be a Banach space. For a topological space <i>X</i>, let <span>\\({{\\cal C}_b}(X,E)\\)</span> be the space of all bounded continuous <i>E</i>-valued functions on <i>X</i>, and let <span>\\({{\\cal C}_K}(X,E)\\)</span> be the subspace of <span>\\({{\\cal C}_b}(X,E)\\)</span> consisting of all functions having a pre-compact image in <i>E</i>. We show that <span>\\({{\\cal C}_K}(X,E)\\)</span> is isometrically isomorphic to the injective tensor product <span>\\({{\\cal C}_b}(X){{\\hat \\otimes}_\\varepsilon}E\\)</span>, and that <span>\\({{\\cal C}_b}(X,E) = {{\\cal C}_b}(X){{\\hat \\otimes}_\\varepsilon}E\\)</span> if and only if <i>E</i> is finite dimensional. Next, we consider the space Lip(<i>X, E</i>) of <i>E</i>-valued Lipschitz operators on a metric space (<i>X, d</i>) and its subspace Lip<sub><i>K</i></sub>(<i>X, E</i>) of Lipschitz compact operators. Utilizing the results on <span>\\({{\\cal C}_b}(X,E)\\)</span>, we prove that Lip<sub><i>K</i></sub>(<i>X, E</i>) is isometrically isomorphic to a tensor product <span>\\({\\rm{Lip}}(X){{\\hat \\otimes}_\\alpha}E\\)</span>, and that <span>\\({\\rm{Lip}}(X,E) = {\\rm{Lip}}(X){{\\hat \\otimes}_\\alpha}E\\)</span> if and only if <i>E</i> is finite dimensional. Finally, we consider the space <i>D</i><sup>1</sup>(<i>X, E</i>) of continuously differentiable functions on a perfect compact plane set <i>X</i> and show that, under certain conditions, <i>D</i><sup>1</sup>(<i>X, E</i>) is isometrically isomorphic to a tensor product <span>\\({D^1}(X){\\hat \\otimes _\\beta}E\\)</span>.</p></div>","PeriodicalId":0,"journal":{"name":"","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Representing certain vector-valued function spaces as tensor products\",\"authors\":\"M. Abtahi\",\"doi\":\"10.1007/s10476-023-0218-2\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Let <i>E</i> be a Banach space. For a topological space <i>X</i>, let <span>\\\\({{\\\\cal C}_b}(X,E)\\\\)</span> be the space of all bounded continuous <i>E</i>-valued functions on <i>X</i>, and let <span>\\\\({{\\\\cal C}_K}(X,E)\\\\)</span> be the subspace of <span>\\\\({{\\\\cal C}_b}(X,E)\\\\)</span> consisting of all functions having a pre-compact image in <i>E</i>. We show that <span>\\\\({{\\\\cal C}_K}(X,E)\\\\)</span> is isometrically isomorphic to the injective tensor product <span>\\\\({{\\\\cal C}_b}(X){{\\\\hat \\\\otimes}_\\\\varepsilon}E\\\\)</span>, and that <span>\\\\({{\\\\cal C}_b}(X,E) = {{\\\\cal C}_b}(X){{\\\\hat \\\\otimes}_\\\\varepsilon}E\\\\)</span> if and only if <i>E</i> is finite dimensional. Next, we consider the space Lip(<i>X, E</i>) of <i>E</i>-valued Lipschitz operators on a metric space (<i>X, d</i>) and its subspace Lip<sub><i>K</i></sub>(<i>X, E</i>) of Lipschitz compact operators. Utilizing the results on <span>\\\\({{\\\\cal C}_b}(X,E)\\\\)</span>, we prove that Lip<sub><i>K</i></sub>(<i>X, E</i>) is isometrically isomorphic to a tensor product <span>\\\\({\\\\rm{Lip}}(X){{\\\\hat \\\\otimes}_\\\\alpha}E\\\\)</span>, and that <span>\\\\({\\\\rm{Lip}}(X,E) = {\\\\rm{Lip}}(X){{\\\\hat \\\\otimes}_\\\\alpha}E\\\\)</span> if and only if <i>E</i> is finite dimensional. Finally, we consider the space <i>D</i><sup>1</sup>(<i>X, E</i>) of continuously differentiable functions on a perfect compact plane set <i>X</i> and show that, under certain conditions, <i>D</i><sup>1</sup>(<i>X, E</i>) is isometrically isomorphic to a tensor product <span>\\\\({D^1}(X){\\\\hat \\\\otimes _\\\\beta}E\\\\)</span>.</p></div>\",\"PeriodicalId\":0,\"journal\":{\"name\":\"\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0,\"publicationDate\":\"2023-06-08\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://link.springer.com/article/10.1007/s10476-023-0218-2\",\"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://link.springer.com/article/10.1007/s10476-023-0218-2","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Representing certain vector-valued function spaces as tensor products
Let E be a Banach space. For a topological space X, let \({{\cal C}_b}(X,E)\) be the space of all bounded continuous E-valued functions on X, and let \({{\cal C}_K}(X,E)\) be the subspace of \({{\cal C}_b}(X,E)\) consisting of all functions having a pre-compact image in E. We show that \({{\cal C}_K}(X,E)\) is isometrically isomorphic to the injective tensor product \({{\cal C}_b}(X){{\hat \otimes}_\varepsilon}E\), and that \({{\cal C}_b}(X,E) = {{\cal C}_b}(X){{\hat \otimes}_\varepsilon}E\) if and only if E is finite dimensional. Next, we consider the space Lip(X, E) of E-valued Lipschitz operators on a metric space (X, d) and its subspace LipK(X, E) of Lipschitz compact operators. Utilizing the results on \({{\cal C}_b}(X,E)\), we prove that LipK(X, E) is isometrically isomorphic to a tensor product \({\rm{Lip}}(X){{\hat \otimes}_\alpha}E\), and that \({\rm{Lip}}(X,E) = {\rm{Lip}}(X){{\hat \otimes}_\alpha}E\) if and only if E is finite dimensional. Finally, we consider the space D1(X, E) of continuously differentiable functions on a perfect compact plane set X and show that, under certain conditions, D1(X, E) is isometrically isomorphic to a tensor product \({D^1}(X){\hat \otimes _\beta}E\).