English

A note on compact-like semitopological groups

General Topology 2019-08-09 v2 Group Theory

Abstract

The note contains a few results related to separation axioms and automatic continuity of operations in compact-like semitopological groups. In particular, is presented a semiregular semitopological group GG which is not T3T_3. We show that each weakly semiregular compact semitopological group is a topological group. On the other hand, constructed examples of quasiregular T1T_1 compact and T2T_2 sequentially compact quasitopological groups, which are not paratopological groups. Also we prove that a semitopological group (G,τ)(G,\tau) is a topological group provided there exists a Hausdorff topology στ\sigma\supset\tau on GG such that (G,σ)(G,\sigma) is a precompact topological group and (G,τ)(G,\tau) is weakly semiregular or (G,σ)(G,\sigma) is a feebly compact paratopological group and (G,τ)(G,\tau) is T3T_3.

Keywords

Cite

@article{arxiv.1907.11215,
  title  = {A note on compact-like semitopological groups},
  author = {Alex Ravsky},
  journal= {arXiv preprint arXiv:1907.11215},
  year   = {2019}
}

Comments

9 pages; minor updates and corrections. arXiv admin note: text overlap with arXiv:1003.5343

R2 v1 2026-06-23T10:31:09.607Z