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Keywords:
uniformly bounded sequences of continuous real-valued functions; convergence index; spreading models of $l^{1}$; Baire-1 functions
uniformly bounded sequences of continuous real-valued functions; convergence index; spreading models of $l^{1}$; Baire-1 functions
Summary:
Rosenthal in [11] proved that if $(f_{k})$ is a uniformly bounded sequence of real-valued functions which has no pointwise converging subsequence then $(f_{k})$ has a subsequence which is equivalent to the unit basis of $l^{1}$ in the supremum norm. Kechris and Louveau in [6] classified the pointwise convergent sequences of continuous real-valued functions, which are defined on a compact metric space, by the aid of a countable ordinal index ``$\gamma $''. In this paper we prove some local analogues of the above Rosenthal 's theorem (spreading models of $l^{1}$) for a uniformly bounded and pointwise convergent sequence $(f_{k})$ of continuous real-valued functions on a compact metric space for which there exists a countable ordinal $\xi$ such that $\gamma ((f_{n_{k}}))> \omega^{\xi}$ for every strictly increasing sequence $(n_{k})$ of natural numbers. Also we obtain a characterization of some subclasses of Baire-1 functions by the aid of spreading models of $l^{1}$.
References:
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