Eventually Constant and stagnating functions in non-Lindel\"of spaces
Abstract
Inspired by recent work of A. Mardani which elaborates on the elementary fact that for any continuous function , there is an such that for all and , we introduce four properties , , which are different formalizations of the idea vaguely stated as "given a continuous , there is a small subspace of outside of which does not do anything much new". We say that the spaces satisfy the property (resp. ) [resp. ] iff given , then there is a Lindel\"of such that is a singleton (resp. there is a retraction such that ) [resp. ]. ( is defined similarly.) We investigate the relations between these four and other classical topological properties. Two variants of each property are given depending on whether can be chosen to be closed. Here is a sample of our results. An uncountable subspace of a tree of height is -compact iff holds for any metrizable space of cardinality . If is a -strongly collectionwise Hausforff non-metrizable manifold satisfying either a weakening of or , then is -compact. The property holds for any manifold while does not. Under PFA, a locally compact countably tight space for which holds is isocompact, while there are counterexamples under . Some of our results are restatements of other researchers work put in our context.
Keywords
Cite
@article{arxiv.2308.12763,
title = {Eventually Constant and stagnating functions in non-Lindel\"of spaces},
author = {Mathieu Baillif},
journal= {arXiv preprint arXiv:2308.12763},
year = {2024}
}
Comments
35 pages, 4 figures. V3: Corrected inaccuracies in Section 4, added small new results in Sections 4 and 5, and some cosmetic correction