On ``Lipschitz'' subspaces of the space of continuous functions (Q1374549)

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scientific article; zbMATH DE number 1095861
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On ``Lipschitz'' subspaces of the space of continuous functions
scientific article; zbMATH DE number 1095861

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    On ``Lipschitz'' subspaces of the space of continuous functions (English)
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    10 December 1997
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    The main result of the paper is that certain ``good'' closed subspace \(S\) of the Banach space \(C(K)\) of all complex valued functions continuous on a compact metric space \(K\) is ``small''. More precisely, if \(S\) is a closed linear subspace of \(C(K)\) such that for every \(f\in S\) \[ \sup _{\delta >0}\frac {\omega _f(\delta)}{\omega (\delta)}<\infty \] (where \(\omega _f(\delta)=\sup _{\rho (x,y)<\delta}|f(x)-f(y)|\), \(\rho\) is the metric on \(K\), and \(\omega :(0,\infty)\to (0,\infty)\) is an increasing function satisfying \(\lim _{\delta \to 0}\omega (\delta)=0\)), then the subspace is finite dimensional. Let us mention that \(L^p\)-version of this result has been derived by \textit{A. Grothendieck} [Can. J. Math. 6, 158-160 (1954; Zbl 0055.09802)].
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    Banach space
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    modulus of continuity
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    closed graph theorem
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