Amalgamating inverse semigroups over ample semigroups

We consider semigroup amalgams (S; T1, T2) in which T1 and T2 are inverse semigroups and S is a non-inverse semigroup. They are known to be non-embeddable if T1 and T2 are both groups (Clifford semigroups), but S is not such. We prove that (S; T1, T2) is non-embeddable if S is a non-inverse ample se...

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Bibliographic Details
Main Author: Nasir Sohail
Format: Article
Language:English
Published: Estonian Academy Publishers 2025-01-01
Series:Proceedings of the Estonian Academy of Sciences
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Online Access:https://kirj.ee/wp-content/plugins/kirj/pub/proc-1-2025-50-61_20250128193135.pdf
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Summary:We consider semigroup amalgams (S; T1, T2) in which T1 and T2 are inverse semigroups and S is a non-inverse semigroup. They are known to be non-embeddable if T1 and T2 are both groups (Clifford semigroups), but S is not such. We prove that (S; T1, T2) is non-embeddable if S is a non-inverse ample semigroup. By introducing the notion of rich ampleness, we determine some necessary and sufficient conditions for the weak embedding of (S; T1, T2) in an inverse semigroup. In particular, (S; T1, T2) is shown to be weakly embeddable in a group if T1 and T2 are groups. A rudimentary analysis of the novel classes of rich ample semigroups is also provided.
ISSN:1736-6046
1736-7530