کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4658036 1633077 2016 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Selective but not Ramsey
ترجمه فارسی عنوان
انتخابی اما نه رمزی
کلمات کلیدی
فضای رامزی؛ اولترافیلورهای انتخابی
موضوعات مرتبط
مهندسی و علوم پایه ریاضیات هندسه و توپولوژی
چکیده انگلیسی

We give a partial answer to the following question of Dobrinen: For a given topological Ramsey space RR, are the notions of selective for RR and Ramsey for RR equivalent? Every topological Ramsey space RR has an associated notion of Ramsey ultrafilter for RR and selective ultrafilter for RR (see [1]). If RR is taken to be the Ellentuck space then the two concepts reduce to the familiar notions of Ramsey and selective ultrafilters on ω; so by a well-known result of Kunen the two are equivalent. We give the first example of an ultrafilter on a topological Ramsey space that is selective but not Ramsey for the space.We show that for the topological Ramsey space R1R1 from [2], the notions of selective for R1R1 and Ramsey for R1R1 are not equivalent. In particular, we prove that forcing with a closely related topological Ramsey space using almost-reduction, adjoins an ultrafilter that is selective but not Ramsey for R1R1.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Topology and its Applications - Volume 202, 1 April 2016, Pages 61–69
نویسندگان
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