Title of article :
Sharp bases and weakly uniform bases versus point-countable bases
Author/Authors :
Arhangelʹski??، نويسنده , , A.V. and Just، نويسنده , , W. and Rezniczenko، نويسنده , , E.A. and Szeptycki، نويسنده , , P.J.، نويسنده ,
Issue Information :
دوماهنامه با شماره پیاپی سال 2000
Abstract :
A base B for a topological space X is said to be sharp if for every x∈X and every sequence (Un)n∈ω of pairwise distinct elements of B with x∈Un for all n the set {⋂i<nUi: n∈ω} forms a base at x. Sharp bases of T0-spaces are weakly uniform. We investigate which spaces with sharp bases or weakly uniform bases have point-countable bases or are metrizable. In particular, Davis, Reed, and Wage had constructed in a 1976 paper a consistent example of a Moore space with weakly uniform base, but without a point-countable base. They asked whether such an example can be constructed in ZFC. We partly answer this question by showing that under CH, every first-countable space with a weakly uniform base and at most ℵω isolated points has a point-countable base.
Keywords :
Sharp base , Continuum hypothesis , Weakly uniformbase , Elementary submodel , k-finite , ? in ? family , k-countable , Point-countable base
Journal title :
Topology and its Applications
Journal title :
Topology and its Applications