کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4660248 1344357 2008 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Nagata's conjecture and countably compact hulls in generic extensions
موضوعات مرتبط
مهندسی و علوم پایه ریاضیات هندسه و توپولوژی
پیش نمایش صفحه اول مقاله
Nagata's conjecture and countably compact hulls in generic extensions
چکیده انگلیسی

Nagata conjectured that every M-space is homeomorphic to a closed subspace of the product of a countably compact space and a metric space. Although this conjecture was refuted by Burke and van Douwen, and A. Kato, independently, but we can show that there is a c.c.c. poset P of size ω2 such that in VP Nagata's conjecture holds for each first countable regular space from the ground model (i.e. if a first countable regular space X∈V is an M-space in VP then it is homeomorphic to a closed subspace of the product of a countably compact space and a metric space in VP). By a result of Morita, it is enough to show that every first countable regular space from the ground model has a first countable countably compact extension in VP. As a corollary, we also obtain that every first countable regular space from the ground model has a maximal first countable extension in model VP.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Topology and its Applications - Volume 155, Issue 4, 1 January 2008, Pages 347-353