Title of article :
Fréchet–Urysohn for finite sets, II
Author/Authors :
Gruenhage، نويسنده , , Gary and Szeptycki، نويسنده , , Paul J.، نويسنده ,
Issue Information :
دوماهنامه با شماره پیاپی سال 2007
Abstract :
We continue our study [G. Gruenhage, P.J. Szeptycki, Fréchet Urysohn for finite sets, Topology Appl. 151 (2005) 238–259] of several variants of the property of the title. We answer a question from that paper by showing that a space defined in a natural way from a certain Hausdorff gap is a Fréchet α 2 space which is not Fréchet–Urysohn for 2-point sets (FU2), and answer a question of Hrušák by showing that under MA ω 1 , no such “gap space” is FU2. We also introduce versions of the properties which are defined in terms of “selection principles”, give examples when possible showing that the properties are distinct, and discuss relationships of these properties to convergence in product spaces, to the α i -spaces of A.V. Arhangelʹskii, and to topological games.
Keywords :
? i -spaces , Fréchet–Urysohn , ?-network
Journal title :
Topology and its Applications
Journal title :
Topology and its Applications