A new order for ideal sequential compactness
Abstract
Let be an ideal on and be a topological space. A sequence in is -convergent if there is such that for every open neighborhood of . We examine the following variant of sequential compactness associated with : is if for every sequence in there is such that is -convergent. We introduce a new preorder on ideals, denoted , such that implies that every space is . Our main result states that under CH the above implication can be reversed in the case of ideals and . We compare with the Kat\v{e}tov order and study the relation among some well-known ideals (e.g. the van der Waerden ideal consisting of all subsets of that do not contain arbitrary long finite arithmetic progressions). As a consequence, we answer two open questions posed by Filip\'{o}w and Tryba in [Top. App. {\textbf{178}} (2014), 438--452] concerning comparison of with the class of sequentially compact spaces.
Cite
@article{arxiv.2603.01114,
title = {A new order for ideal sequential compactness},
author = {Adam Kwela and Dorota Lesner},
journal= {arXiv preprint arXiv:2603.01114},
year = {2026}
}