English

On subgroups of saturated or totally bounded paratopological groups

Group Theory 2010-03-30 v1

Abstract

A paratopological group GG is saturated if the inverse U1U^{-1} of each non-empty set UGU\subset G has non-empty interior. It is shown that a [first-countable] paratopological group HH is a closed subgroup of a saturated (totally bounded) [abelian] paratopological group if and only if HH admits a continuous bijective homomorphism onto a (totally bounded) [abelian] topological group GG [such that for each neighborhood UHU\subset H of the unit ee there is a closed subset FGF\subset G with eh1(F)Ue\in h^{-1}(F)\subset U]. As an application we construct a paratopological group whose character exceeds its π\pi-weight as well as the character of its group reflexion. Also we present several examples of (para)topological groups which are subgroups of totally bounded paratopological groups but fail to be subgroups of regular totally bounded paratopological groups.

Keywords

Cite

@article{arxiv.1003.5355,
  title  = {On subgroups of saturated or totally bounded paratopological groups},
  author = {Taras Banakh and Alex Ravsky},
  journal= {arXiv preprint arXiv:1003.5355},
  year   = {2010}
}

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14 pages