Topology and its Applications ( IF 0.6 ) Pub Date : 2021-04-13 , DOI: 10.1016/j.topol.2021.107674 Wei He , Dekui Peng , Mikhail Tkachenko , Heng Zhang
Our main objective is a further study of -factorizability in topological groups as defined in Zhang, Peng, He, Tkachenko (2020) [15]. We focus on topological-algebraic implications of -factorizability such as τ-precompactness, pseudo-τ-compactness and τ-fineness. We also study products of topological groups and present necessary and sufficient conditions on the factors guaranteeing the -factorizability of products. Our main technical tool for this study is the new notion of τ-fine topological group, where is a cardinal. We prove the following dichotomy theorem: Every -factorizable topological group is either -factorizable or -fine.
Another dichotomy is established for the product of two groups. We prove that if the product of topological groups is -factorizable, then for every cardinal , either G is τ-fine or H is pseudo-τ-compact. We also show that the product is -factorizable provided G is a metrizable topological group with and H is a τ-fine topological group with .
It is also proved that the product is -factorizable (-factorizable) whenever G is an arbitrary -factorizable (-factorizable) topological group and H is a locally compact separable metrizable topological group.
中文翻译:
和τ-精细拓扑群的可分解性
我们的主要目标是对 Zhang,Peng,He,Tkachenko(2020)中定义的拓扑群中的可分解性[15]。我们专注于...的拓扑-代数含义-可分解性,例如τ-预紧实度,伪τ-紧实度和τ细度。我们还研究拓扑组的乘积,并就保证安全性的因素提出了充分必要的条件。产品的可分解性。这项研究的主要技术工具是τ-精细拓扑群的新概念,其中是红衣主教 我们证明以下二分定理:可分解的拓扑组是 可分解或 -美好的。
建立了针对两组产品的另一种二分法。我们证明如果产品 的拓扑组是 -可分解的,然后针对每个基数 ,G是τ- fine或H是伪τ- compact。我们还展示了该产品 是 可分解的,前提是G是具有以下特征的可化拓扑组和ħ是τ -精细拓扑群与。
也证明了该产品 是 可分解的(-factorizable)只要G是任意的可分解的(-可分解的拓扑组,而H是局部紧凑的可分离的可量化的拓扑组。