English

A series of series topologies on $\mathbb{N}$

General Topology 2020-04-01 v2

Abstract

Each series n=1an\sum_{n=1}^\infty a_n of real positive terms gives rise to a topology on N={1,2,3,...}\mathbb{N} = \{1,2,3,...\} by declaring a proper subset ANA\subseteq \mathbb{N} to be closed if nAan<\sum_{n\in A} a_n < \infty. We explore the relationship between analytic properties of the series and topological properties on N\mathbb{N}. In particular, we show that, up to homeomorphism, R|\mathbb{R}|-many topologies are generated. We also find an uncountable family of examples {Nα}α[0,1]\{\mathbb{N}_\alpha\}_{\alpha \in [0,1]} with the property that for any α<β\alpha < \beta, there is a continuous bijection NβNα\mathbb{N}_\beta\rightarrow \mathbb{N}_\alpha, but the only continuous functions NαNβ\mathbb{N}_\alpha\rightarrow \mathbb{N}_\beta are constant.

Keywords

Cite

@article{arxiv.1809.04658,
  title  = {A series of series topologies on $\mathbb{N}$},
  author = {Jason DeVito and Zachary Parker},
  journal= {arXiv preprint arXiv:1809.04658},
  year   = {2020}
}

Comments

Final version. To appear in Involve: A Journal of Mathematics