Title of article :
Finite unions of weak -refinable spaces and products of ordinals
Author/Authors :
Peng، نويسنده , , Liang-Xue، نويسنده ,
Issue Information :
دوماهنامه با شماره پیاپی سال 2009
Abstract :
In this note, we show that if X is the union of a finite collection { X i : i = 1 , … , k } of weak θ ¯ -refinable subspaces and e ( X ) = ω , then X is a Lindelöf space. We also show that the product of two ordinals is dually discrete. The last conclusion gives a positive answer to a question of Alas, Junqueira and Wilson.
Keywords :
Dually discrete , Ordinal , Weak ? ¯ -refinable , D-space
Journal title :
Topology and its Applications
Journal title :
Topology and its Applications