کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4657879 1633072 2016 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Two weak forms of countability axioms in free topological groups
موضوعات مرتبط
مهندسی و علوم پایه ریاضیات هندسه و توپولوژی
پیش نمایش صفحه اول مقاله
Two weak forms of countability axioms in free topological groups
چکیده انگلیسی

Given a Tychonoff space X  , let F(X)F(X) and A(X)A(X) be respectively the free topological group and the free Abelian topological group over X   in the sense of Markov. For every n∈Nn∈N, let Fn(X)Fn(X) (resp. An(X)An(X)) denote the subspace of F(X)F(X) (resp. A(X)A(X)) that consists of words of reduced length at most n with respect to the free basis X  . In this paper, we discuss two weak forms of countability axioms in F(X)F(X) or A(X)A(X), namely the csf-countability and snf-countability. We provide some characterizations of the csf-countability and snf  -countability of F(X)F(X) and A(X)A(X) for various classes of spaces X. In addition, we also study the csf-countability and snf  -countability of Fn(X)Fn(X) or An(X)An(X), for n=2,3,4n=2,3,4. Some results of Arhangel'skiı̌ in [1] and Yamada in [20] are generalized. An affirmative answer to an open question posed by Li et al. in [11] is provided.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Topology and its Applications - Volume 207, 1 July 2016, Pages 96–108
نویسندگان
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