It is well-known that the concentric circle space has no $G_\delta $-diagonal nor any countable point-separating open cover. In this paper, we reveal two new properties of the concentric circle space, which are the weak versions of $G_\delta $-diagonal and countable point-separating open cover. Then we introduce two new cardinal functions and sharpen some known cardinal inequalities.
@article{116982,
author = {Shu Hao Sun and Koo Guan Choo},
title = {New properties of the concentric circle space and its applications to cardinal inequalities},
journal = {Commentationes Mathematicae Universitatis Carolinae},
volume = {32},
year = {1991},
pages = {395-403},
zbl = {0772.54004},
mrnumber = {1137802},
language = {en},
url = {http://dml.mathdoc.fr/item/116982}
}
Sun, Shu Hao; Choo, Koo Guan. New properties of the concentric circle space and its applications to cardinal inequalities. Commentationes Mathematicae Universitatis Carolinae, Tome 32 (1991) pp. 395-403. http://gdmltest.u-ga.fr/item/116982/
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