Cancellative conjugation semigroups and monoids

• Autor(a) principal: Garrão, Ana Paula
• Data de Publicação: 2020
• Outros Autores: Martins-Ferreira, Nelson, Raposo, Margarida, Sobral, Manuela
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/89458; https://doi.org/10.1007/s00233-019-10070-9
• topic: Admissibility diagrams; Weakly Mal’tsev category; Conjugation semigroups; Internal monoid; Internal groupoid

We show that the category of cancellative conjugation semigroups is weakly Mal’tsev and give a characterization of all admissible diagrams there. In the category of cancellative conjugation monoids we describe, for Schreier split epimorphisms with codomain B and kernel X, all morphisms h:X→B which induce a reflexive graph, an internal category or an internal groupoid. We describe Schreier split epimorphisms in terms of external actions and consider the notions of precrossed semimodule, crossed semimodule and crossed module in the context of cancellative conjugation monoids. In this category we prove that a relative version of the so-called “Smith is Huq” condition for Schreier split epimorphisms holds as well as other relative conditions.