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JOURNALS // Algebra and Discrete Mathematics // Archive

Algebra Discrete Math., 2003 Issue 4, Pages 1–20 (Mi adm389)

This article is cited in 9 papers

RESEARCH ARTICLE

On subgroups of saturated or totally bounded paratopological groups

Taras Banakhab, Sasha Ravskyb

a Instytut Matematyki, Akademia Świętokrzyska in Kielce, Świętokrzyska 15, Kielce, 25406, Poland
b Department of Mathematics, Ivan Franko Lviv National University, Universytetska, 1 Lviv, 79000, Ukraine

Abstract: A paratopological group $G$ is saturated if the inverse $U^{-1}$ of each non-empty set $U\subset G$ has non-empty interior. It is shown that a [first-countable] paratopological group $H$ is a closed subgroup of a saturated (totally bounded) [abelian] paratopological group if and only if $H$ admits a continuous bijective homomorphism onto a (totally bounded) [abelian] topological group $G$ [such that for each neighborhood $U\subset H$ of the unit $e$ there is a closed subset $F\subset G$ with $e\in h^{-1}(F)\subset U$]. As an application we construct a paratopological group whose character exceeds its $\pi$-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: saturated paratopological group, group reflexion.

MSC: 22A15, 54H10, 54H11

Language: English



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