Mathematics

This is the first talk in a series of seminars about thetheory of stacks in algebraic geometry. In the first part of the talk I willdiscuss the theory of representable functors (in particular Yoneda lemmaand universal object of a functor), in the second part group objects in acategory and their actions are discussed, using the results introduced inthe first part.I will follow the notes by Angelo Vistoli on algebraic stacks:http://homepage.sns.it/vistoli/descent.pdf