Selectivity properties of spaces
arXiv:1910.10634
Abstract
This paper addresses several questions of Feng, Gruenhage, and Shen which arose from Michael's theory of continuous selections from countable spaces. We construct an example of a space which is -selective but not -selective from , and an -selective space which is not selective for a -point ultrafilter from the assumption of . We also produce examples of Fréchet spaces where countable subsets are first countable which are not -selective.