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Lipschitz-free spaces and approximating sequences of projections
被引:2
|作者:
Godefroy, Gilles
[1
]
机构:
[1] Inst Math Jussieu Paris Rive Gauche, Paris, France
关键词:
Lipschitz-free spaces;
Absolute extendability;
Finite-dimensional decompositions;
Bounded approximation properties;
FREE BANACH-SPACES;
DESCRIPTIVE COMPLEXITY;
EXTENSIONS;
DECOMPOSITIONS;
PROPERTY;
SUBSETS;
FAMILY;
BASES;
D O I:
10.1007/s43037-024-00332-2
中图分类号:
O29 [应用数学];
学科分类号:
070104 ;
摘要:
The Lipschitz-free space F(M)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathcal {F}}(M)$$\end{document} has an F.D.D. when M is a separable L1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathcal {L}}_1$$\end{document}-Banach space, or when M subset of Rn\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$M\subset {\mathbb {R}}<^>n$$\end{document} is a somewhat regular subset. The interplay between the existence of extension operators for Lipschitz maps and the (pi)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\pi )$$\end{document}-property in Lipschitz-free spaces is investigated. If M is an arbitrary metric space, then F(M)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathcal {F}}(M)$$\end{document} has the (pi)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\pi )$$\end{document}-property up to a universal logarithmic factor. It follows in particular that the (pi)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\pi )$$\end{document}-property up to a logarithmic factor fails to imply the approximation property. A list of commented open problems is provided.
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