Title: An introduction to pretorsion theories (based on the collaboration with Alberto Facchini, Carmelo Finocchiaro, Francis Borceux, Federico Campanini, Aline Michel and Walter Tholen) Abstract: The notion of pretorsion theory is a natural extension of the classical notion of torsion theory in an abelian category. The idea is to associate, with any pair (T , F) […]

Title: Galois theory and homology in quasi-abelian functor categories Abstract: The aim of this talk is to give an introduction to the categorical theory of (higher) central extensions and of generalized Hopf formulae for homology, and to apply these methods to the study of, in particular, the category Grpdn(A) of internal n-fold groupoids in a […]