English

A non-polybounded absolutely closed $36$-Shelah group

Group Theory 2022-12-06 v1 General Topology Logic

Abstract

For every infinite cardinal κ\kappa with κ+=2κ\kappa^+=2^\kappa we construct a group GG of cardinality G=κ+|G|=\kappa^+ such that (i) GG is 3636-Shelah, which means that A36=GA^{36}=G for any subset AGA\subseteq G of cardinality A=G|A|=|G|; (ii) GG is absolutely T ⁣1S\mathsf{T_{\!1}S}-closed and projectively T ⁣1S\mathsf{T_{\!1}S}-discrete, which means that for every homomorphism h:GYh:G\to Y to a T1T_1 topological semigroup YY the image h[G]h[G] is a closed discrete subspace of YY, (iii) GG cannot be covered by finitely many algebraic subsets, i.e., subsets of the form {xG:xc1xc2xcn=e}\{x\in G:xc_1xc_2\cdots xc_n=e\} for some c1,c2,,cnGc_1,c_2,\cdots,c_n\in G.

Keywords

Cite

@article{arxiv.2212.01750,
  title  = {A non-polybounded absolutely closed $36$-Shelah group},
  author = {Taras Banakh},
  journal= {arXiv preprint arXiv:2212.01750},
  year   = {2022}
}

Comments

23 pages

R2 v1 2026-06-28T07:21:25.293Z