On Definably Compact Semigroups in o-Minimal Structures

Fuente: arXiv
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Autore principale: Magalhães, Eduardo
Natura: Preprint
Pubblicazione: 2025
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author Magalhães, Eduardo
author_facet Magalhães, Eduardo
contents In this paper, we study definably compact semigroups in o-minimal structures, aiming to extend the theory of definable groups to a broader algebraic setting. We show that any definably compact semigroup contains idempotents and admits a unique minimal ideal as well as minimal left and right ideals, all of which are definable and definably compact. We prove that cancellativity characterizes definable groups among definably compact semigroups, and that any definably compact subsemigroup of a definable group is itself a subgroup. In the completely simple case, we classify definable subsemigroups via a definable Rees matrix decomposition and analyse when results from the theory of definable groups extend to this setting.
format Preprint
id arxiv_https___arxiv_org_abs_2507_19162
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On Definably Compact Semigroups in o-Minimal Structures
Magalhães, Eduardo
Logic
03C64, 20M99, 22A15
In this paper, we study definably compact semigroups in o-minimal structures, aiming to extend the theory of definable groups to a broader algebraic setting. We show that any definably compact semigroup contains idempotents and admits a unique minimal ideal as well as minimal left and right ideals, all of which are definable and definably compact. We prove that cancellativity characterizes definable groups among definably compact semigroups, and that any definably compact subsemigroup of a definable group is itself a subgroup. In the completely simple case, we classify definable subsemigroups via a definable Rees matrix decomposition and analyse when results from the theory of definable groups extend to this setting.
title On Definably Compact Semigroups in o-Minimal Structures
topic Logic
03C64, 20M99, 22A15
url https://arxiv.org/abs/2507.19162