Resolvability of spaces having small spread or extent |
| |
Authors: | Istvá n Juhá sz,Lajos Soukup |
| |
Affiliation: | a Alfréd Rényi Institute of Mathematics, Hungary b Eötvös University of Budapest, Hungary |
| |
Abstract: | In a recent paper O. Pavlov proved the following two interesting resolvability results:- (1)
- If a T1-space X satisfies Δ(X)>ps(X) then X is maximally resolvable.
- (2)
- If a T3-space X satisfies Δ(X)>pe(X) then X is ω-resolvable.
Here ps(X) (pe(X)) denotes the smallest successor cardinal such that X has no discrete (closed discrete) subset of that size and Δ(X) is the smallest cardinality of a non-empty open set in X.In this note we improve (1) by showing that Δ(X)>ps(X) can be relaxed to Δ(X)?ps(X), actually for an arbitrary topological space X. In particular, if X is any space of countable spread with Δ(X)>ω then X is maximally resolvable.The question if an analogous improvement of (2) is valid remains open, but we present a proof of (2) that is simpler than Pavlov's. |
| |
Keywords: | 54A25 54B05 |
本文献已被 ScienceDirect 等数据库收录! |
|