A Note on 5-spaces
نویسنده
چکیده
An S-space is a normal topological space in which each covering by open sets has a refinement which is star-finite, that is, each set of the refinement meets only a finite number of sets of the refinement. Thus a compact ( = bicompact) space is an S-space, and an S-space is paracompact [ l ] . 1 In this note we discuss cartesian products in which one of the factors is an S-space. We show that if the other factor is compact, then the product is an S-space, and the dimension of the product does not exceed the sum of the dimensions of the factors. However, if both factors are S-spaces, the product need not be an S-space.
منابع مشابه
A note on lacunary series in $mathcal{Q}_K$ spaces
In this paper, under the condition that $K$ is concave, we characterize lacunary series in $Q_{k}$ spaces. We improve a result due to H. Wulan and K. Zhu.
متن کاملA note on soft topological spaces
This paper demonstrates the redundancies concerning the increasing popular ``soft set" approaches to general topologies. It is shown that there is a complement preserving isomorphism (preserving arbitrary $widetilde{bigcup}$ and arbitrary $widetilde{bigcap}$) between the lattice ($mathcal{ST}_E(X,E),widetilde{subset}$) of all soft sets on $X$ with the whole parameter set $E$ as domains and the ...
متن کاملA Note on Belief Structures and S-approximation Spaces
We study relations between evidence theory and S-approximation spaces. Both theories have their roots in the analysis of Dempsterchr('39')s multivalued mappings and lower and upper probabilities, and have close relations to rough sets. We show that an S-approximation space, satisfying a monotonicity condition, can induce a natural belief structure which is a fundamental block in evidence theory...
متن کاملA note on the remainders of rectifiable spaces
In this paper, we mainly investigate how the generalized metrizability properties of the remainders affect the metrizability of rectifiable spaces, and how the character of the remainders affects the character and the size of a rectifiable space. Some results in [A. V. Arhangel'skii and J. Van Mill, On topological groups with a first-countable remainder, Topology Proc. 42 (2013...
متن کاملA note on convergence in fuzzy metric spaces
The sequential $p$-convergence in a fuzzy metric space, in the sense of George and Veeramani, was introduced by D. Mihet as a weaker concept than convergence. Here we introduce a stronger concept called $s$-convergence, and we characterize those fuzzy metric spaces in which convergent sequences are $s$-convergent. In such a case $M$ is called an $s$-fuzzy metric. If $(N_M,ast)$ is a fuzzy metri...
متن کامل