کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4658354 1633093 2015 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Partitions of 2ω2ω and completely ultrametrizable spaces
موضوعات مرتبط
مهندسی و علوم پایه ریاضیات هندسه و توپولوژی
پیش نمایش صفحه اول مقاله
Partitions of 2ω2ω and completely ultrametrizable spaces
چکیده انگلیسی

We prove that, for every n  , the topological space ωnω (where ωnωn has the discrete topology) can be partitioned into ℵnℵn copies of the Baire space. Using this fact, we then prove two new theorems about completely ultrametrizable spaces. We say that Y is a condensation of X   if there is a continuous bijection f:X→Yf:X→Y. First, it is proved that ωωωω is a condensation of ωnω if and only if ωωωω can be partitioned into ℵnℵn Borel sets, and some consistency results are given regarding such partitions. It is also proved that it is consistent with ZFC   that, for any n<ωn<ω, c=ωnc=ωn and there are exactly n+3n+3 similarity types of perfect completely ultrametrizable spaces of size cc. These results answer two questions of the first author from [1].

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Topology and its Applications - Volume 184, 1 April 2015, Pages 61–71
نویسندگان
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