Property C ′ ′ , strong measure zero sets and subsets of the plane
نویسنده
چکیده
Let X be a set of reals. We show that • X has property C′′ of Rothberger iff for all closed F ⊆ R×R with vertical sections Fx (x ∈ X) null, ⋃ x∈X Fx is null; • X has strong measure zero iff for all closed F ⊆ R×R with all vertical sections Fx (x ∈ R) null, x∈X Fx is null.
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تاریخ انتشار 2007