کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4658502 1633101 2014 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Star versions of the Menger property
ترجمه فارسی عنوان
نسخه های ستاره ای از اموال منگر
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه ریاضیات هندسه و توپولوژی
چکیده انگلیسی

A space X   is said to be star-Menger (resp., strongly star-Menger) if for each sequence {Un:n∈ω}{Un:n∈ω} of open covers of X  , there are finite subfamilies Vn⊂UnVn⊂Un (resp., finite subsets Fn⊂XFn⊂X) such that {St(⋃Vn,Un):n∈ω}{St(⋃Vn,Un):n∈ω} (resp., {St(Fn,Un):n∈ω}{St(Fn,Un):n∈ω}) is a cover of X. These star versions of the Menger property were first introduced and studied in Kočinac [14] and [15]. In this paper, answering Song's question, we show that the extent of a regular strongly star-Menger space cannot exceed the continuum cc. Star-Menger Pixley–Roy hyperspaces PR(X)PR(X) are also investigated. We show that if a space X   is regular and PR(X)PR(X) is star-Menger, then the cardinality of X   is less than cc and every finite power of X is Menger.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Topology and its Applications - Volume 176, 1 October 2014, Pages 22–34
نویسندگان
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