On subgroups of saturated or totally bounded paratopological groups

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\...

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Bibliographic Details
Date:2018
Main Authors: Banakh, Taras, Ravsky, Sasha
Format: Article
Language:English
Published: Lugansk National Taras Shevchenko University 2018
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Online Access:https://admjournal.luguniv.edu.ua/index.php/adm/article/view/969
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Journal Title:Algebra and Discrete Mathematics

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Algebra and Discrete Mathematics
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Summary: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.