Centre for Mathematics, University of Coimbra

<Reference List>
Type:	Preprint
National /International:	International
Title:	Some remarks on pullbacks in Gumm categories
Publication Date:	2014
Authors:	- Marino Gran - Diana Rodelo
Abstract:	We extend some properties of pullbacks which are known to hold in a Mal’tsev context to the more general context of Gumm categories. The varieties of universal algebras which are Gumm categories are precisely the congruence modular ones. These properties lead to a simple alternative proof of the known property that central extensions and normal extensions coincide for any Galois structure associated with a Birkhoff subcategory of an exact Goursat category.
Institution:	DMUC 14-31
Online version:	http://www.mat.uc.pt...prints/eng_2014.html
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