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Decomposing symmetrically continuous and Sierpinski-Zygmund functions into continuous functions
Authors:Krzysztof Ciesielski
Abstract:
In this paper we will investigate the smallest cardinal number $kappa$ such that for any symmetrically continuous function $fcolonmathbb{R}tomathbb{R}$ there is a partition ${X_xicolonxi<kappa}$ of $mathbb{R}$ such that every restriction $frestriction X_xicolon X_xitomathbb{R}$ is continuous. The similar numbers for the classes of Sierpinski-Zygmund functions and all functions from $mathbb{R}$ to $mathbb{R}$ are also investigated and it is proved that all these numbers are equal. We also show that $mathrm{cf}(mathfrak{c})leqkappaleqmathfrak{c}$ and that it is consistent with ZFC that each of these inequalities is strict.

Keywords:Decomposition number   symmetrically continuous functions   Sierpi'nski-Zygmund functions
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