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We show that the adjunction between monoids and groups obtained via the Grothendieck group construction is admissible, relatively to surjective homomorphisms, in the sense of categorical Galois theory. The central extensions with respect to this Galois structure turn out to be the so-called special homogeneous surjections.
@article{TAC_2014_29_a6, author = {Andrea Montoli and Diana Rodelo and Tim Van der Linden}, title = {A {Galois} theory for monoids}, journal = {Theory and applications of categories}, pages = {198--214}, publisher = {mathdoc}, volume = {29}, year = {2014}, language = {en}, url = {http://geodesic.mathdoc.fr/item/TAC_2014_29_a6/} }
Andrea Montoli; Diana Rodelo; Tim Van der Linden. A Galois theory for monoids. Theory and applications of categories, Tome 29 (2014), pp. 198-214. http://geodesic.mathdoc.fr/item/TAC_2014_29_a6/