scholarly journals Star versions of the Hurewicz basis covering property and strong measure zero spaces

2020 ◽  
Vol 44 (3) ◽  
pp. 1042-1053
Author(s):  
Manoj BHARDWAJ ◽  
Alexander V. OSIPOV
1998 ◽  
Vol 63 (1) ◽  
pp. 301-324 ◽  
Author(s):  
Andrej Nowik ◽  
Marion Scheepers ◽  
Tomasz Weiss

AbstractWe prove the following theorems:(1) IfXhas strong measure zero and ifYhas strong first category, then their algebraic sum has property S0.(2) IfXhas Hurewicz's covering property, then it has strong measure zero if, and only if, its algebraic sum with any first category set is a first category set.(3) IfXhas strong measure zero and Hurewicz's covering property then its algebraic sum with any set inis a set in. (is included in the class of sets always of first category, and includes the class of strong first category sets.)These results extend: Fremlin and Miller's theorem that strong measure zero sets having Hurewicz's property have Rothberger's property, Galvin and Miller's theorem that the algebraic sum of a set with the γ-property and of a first category set is a first category set, and Bartoszyfński and Judah's characterization of-sets. They also characterize the property (*) introduced by Gerlits and Nagy in terms of older concepts.


1999 ◽  
Vol 64 (3) ◽  
pp. 1295-1306 ◽  
Author(s):  
Marion Scheepers

AbstractIn a previous paper—[17]—we characterized strong measure zero sets of reals in terms of a Ramseyan partition relation on certain subspaces of the Alexandroff duplicate of the unit interval. This framework gave only indirect access to the relevant sets of real numbers. We now work more directly with the sets in question, and since it costs little in additional technicalities, we consider the more general context of metric spaces and prove:1. If a metric space has a covering property of Hurewicz and has strong measure zero, then its product with any strong measure zero metric space is a strong measure zero metric space (Theorem 1 and Lemma 3).2. A subspace X of a σ-compact metric space Y has strong measure zero if, and only if, a certain Ramseyan partition relation holds for Y (Theorem 9).3. A subspace X of a σ-compact metric space Y has strong measure zero in all finite powers if, and only if, a certain Ramseyan partition relation holds for Y (Theorem 12).Then 2 and 3 yield characterizations of strong measure zeroness for σ-totally bounded metric spaces in terms of Ramseyan theorems.


2016 ◽  
Vol 55 (1-2) ◽  
pp. 105-131
Author(s):  
Michael Hrušák ◽  
Wolfgang Wohofsky ◽  
Ondřej Zindulka

1990 ◽  
Vol 55 (2) ◽  
pp. 674-677
Author(s):  
Janusz Pawlikowski

AbstractAny finite support iteration of posets with precalibre ℵ1 which has the length of cofinahty greater than ω1 yields a model for the dual Borel conjecture in which the real line is covered by ℵ1 strong measure zero sets.


2001 ◽  
Vol 170 (3) ◽  
pp. 219-229 ◽  
Author(s):  
Aapo Halko ◽  
Saharon Shelah

2009 ◽  
Vol 42 (1) ◽  
pp. 73-80
Author(s):  
Małgorzata Filipczak ◽  
Elžbieta Wagner-Bojakowska

Abstract We consider two kinds of small subsets of the real line: the sets of strong measure zero and the microscopic sets. There are investigated the properties of these sets. The example of a microscopic set, which is not a set of strong measure zero, is given.


1988 ◽  
Vol 102 (3) ◽  
pp. 681
Author(s):  
Jaime Ihoda ◽  
Saharon Shelah

2014 ◽  
Vol 165 (9) ◽  
pp. 1445-1469 ◽  
Author(s):  
Kojiro Higuchi ◽  
Takayuki Kihara

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