English

Counting overweight spaces

General Topology 2020-06-05 v1

Abstract

Let c=2^aleph0 denote the cardinality of the continuum and let a,b,k be infinite cardinal numbers with a<b\leq 2^a. We show that there exist precisely 2^b T0-spaces of size a and weight b up to homeomorphism. Among these non-homeomorphic spaces we track down (1) 2^b zero-dimensional, scattered, paracompact, perfectly normal spaces (which are also extremally disconnected in case that b=2^a); (2) 2^b connected and locally connected Hausdorff spaces; (3) 2^b pathwise connected and locally pathwise connected, paracompact, perfectly normal spaces provided that a\geq c; (4) 2^b connected, nowhere locally connected, totally pathwise disconnected, paracompact, perfectly normal spaces provided that a\geq c; (5) 2^b scattered, compact T1-spaces; (6) 2^b connected, locally connected, compact T1-spaces; (7) 2^b pathwise connected and scattered, compact T0-spaces; (8) 2^b scattered, paracompact P_k-spaces whenever a^{<k}=a and b^{<k}=b and 2^b>2^a.

Keywords

Cite

@article{arxiv.2006.02880,
  title  = {Counting overweight spaces},
  author = {Gerald Kuba},
  journal= {arXiv preprint arXiv:2006.02880},
  year   = {2020}
}
R2 v1 2026-06-23T16:03:29.125Z