caa a22 4500 467882711 CHVBK 20180406152724.0 cr unu---uuuuu 170328e20060801xx s 000 0 eng 10.1007/s10485-006-9026-7 doi (NATIONALLICENCE)springer-10.1007/s10485-006-9026-7 Rossi Valentina Dipartimento di Matematica e Informatica, Università degli Studi di Udine, Via delle Scienze 206, 33100, Udine, Italy aut Admissible Galois Structures and Coverings in Regular Mal'cev Categories [Elektronische Daten] [Valentina Rossi] Given a regular Gumm category $\mathcal C$ such that any regular epimorphism is effective for descent, we prove that any Birkhoff subcategory $\mathcal X$ in $\mathcal C$ gives rise to an admissible Galois structure. This result allows one to consider some new applications of the categorical Galois theory in the context of topological algebras. Given a regular Mal'cev category $\mathcal C$ , we first characterize the coverings of the Galois structure $\bar{\Gamma}_1$ induced by the subcategory $\mathcal C_{Ab}$ of the abelian objects in $\mathcal C$ . Then we consider $\mathcal C$ as a subcategory of the category $Eq(\mathcal C)$ of the equivalence relations in $\mathcal C$ , and we characterize the coverings of the corresponding Galois structure $\bar{\Gamma}_2$ . By composing the Galois structures $\bar{\Gamma}_1$ and $\bar{\Gamma}_2$ we obtain the Galois structure $\bar{\Gamma}$ induced by $\mathcal C_{Ab}$ as a subcategory of $Eq(\mathcal C)$ . We give the characterization of the $\bar{\Gamma}$ -coverings in terms of the coverings of $\bar{\Gamma}_1$ and $\bar{\Gamma}_2$ . Springer Science + Business Media B.V., 2006 categorical Galois theory nationallicence coverings nationallicence modular varieties nationallicence topological groups and topological Mal'cev algebras nationallicence Applied Categorical Structures Kluwer Academic Publishers 14/4(2006-08-01), 291-311 0927-2852 14:4<291 2006 14 10485 https://doi.org/10.1007/s10485-006-9026-7 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10485-006-9026-7 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Rossi Valentina Dipartimento di Matematica e Informatica, Università degli Studi di Udine, Via delle Scienze 206, 33100, Udine, Italy aut NATIONALLICENCE 773 0- Applied Categorical Structures Kluwer Academic Publishers 14/4(2006-08-01), 291-311 0927-2852 14:4<291 2006 14 10485 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer