Topology and its Applications ( IF 0.6 ) Pub Date : 2021-07-01 , DOI: 10.1016/j.topol.2021.107764 O.T. Alas , V.V. Tkachuk , R.G. Wilson
We establish that any Hausdorff discretely κ-Lindelöf space X must be κ-Lindelöf if . Besides, in κ-Lindelöf spaces whose tightness does not exceed κ, the property of having pseudocharacter ≤κ must be discretely reflexive. Under the hypothesis we prove that countable pseudocharacter is discretely reflexive in Lindelöf Σ-spaces. If X is a Tychonoff space and for any discrete set , then is a caliber of X, we have the inequality and for any ; this implies that . We also show that the property of having pseudocharacter ≤κ is discretely reflexive in whenever X is a compact space with .
中文翻译:
林德洛夫度和伪特征的离散自反性
我们确定任何 Hausdorff 离散κ -Lindelöf 空间X必须是κ -Lindelöf 如果. 此外,在紧密度不超过κ 的κ -Lindelöf 空间中,具有伪字符≤ κ 的性质必须是离散自反的。根据假设我们证明了可数伪字符在 Lindelöf Σ-空间中是离散自反的。如果X是 Tychonoff 空间并且 对于任何离散集 , 然后 是X的口径,我们有不等式 和 对于任何 ; 这意味着. 我们还表明,具有伪字符 ≤ κ的属性在每当X是紧致空间时.