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The notion of a weakly Mal'tsev category, as it was introduced in 2008 by the third author, is a generalization of the classical notion of a Mal'tsev category. It is well-known that a variety of universal algebras is a Mal'tsev category if and only if its theory admits a Mal'tsev term. In the main theorem of this paper, we prove a syntactic characterization of the varieties that are weakly Mal'tsev categories. We apply our result to the variety of distributive lattices which was known to be a weakly Mal'tsev category before. By a result of Z. Janelidze and the third author, a finitely complete category is weakly Mal'tsev if and only if any internal strong reflexive relation is an equivalence relation. In the last part of this paper, we give a syntactic characterization of those varieties in which any regular reflexive relation is an equivalence relation.
Keywords: weakly Mal'tsev category, weakly Mal'tsev variety, Mal'tsev condition, syntactic characterization, strong relation, pullback injection
@article{TAC_2024_42_a11,
author = {Nadja Egner and Pierre-Alain Jacqmin and Nelson Martins-Ferreira},
title = {A syntactic characterization of weakly {Mal'tsev} varieties},
journal = {Theory and applications of categories},
pages = {314--353},
publisher = {mathdoc},
volume = {42},
year = {2024},
language = {en},
url = {http://geodesic.mathdoc.fr/item/TAC_2024_42_a11/}
}
TY - JOUR AU - Nadja Egner AU - Pierre-Alain Jacqmin AU - Nelson Martins-Ferreira TI - A syntactic characterization of weakly Mal'tsev varieties JO - Theory and applications of categories PY - 2024 SP - 314 EP - 353 VL - 42 PB - mathdoc UR - http://geodesic.mathdoc.fr/item/TAC_2024_42_a11/ LA - en ID - TAC_2024_42_a11 ER -
Nadja Egner; Pierre-Alain Jacqmin; Nelson Martins-Ferreira. A syntactic characterization of weakly Mal'tsev varieties. Theory and applications of categories, Hofstra Festschrift, Tome 42 (2024), pp. 314-353. http://geodesic.mathdoc.fr/item/TAC_2024_42_a11/