Geodesic
New properties of the concentric circle space and its applications to cardinal inequalities
Commentationes Mathematicae Universitatis Carolinae, Tome 32 (1991) no. 2, pp. 395-403 Cet article a éte moissonné depuis la source Czech Digital Mathematics Library

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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.
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.
Classification : 54A25, 54D20, 54G05
Keywords: concentric circle space; weak $G_\delta $-diagonal; point-separating $^\ast $-open cover; cardinal function 
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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) no. 2, pp. 395-403. http://geodesic.mathdoc.fr/item/CMUC_1991_32_2_a22/

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