Seminario: Sheaves and Cauchy-complete objects in Doctrines

Venerdì 7 Marzo 2014, ore 15:30 - Aula 1BC45 - Fabio Pasquali



Venerdì 7 Marzo 2014 alle ore 15:30 in aula 1BC45, il dott. Fabio Pasquali (Universiteit Utrecht - postdoc) terrà un seminario dal titolo "Sheaves and Cauchy-complete objects in Doctrines".

It has been Walters who firstly noted the link between the notion of sheaf and that of Lawvere Cauchy-completeness. In particular he proved that the topos of sheaves on a site (C,J) is equivalent to the bicategory of symmetric Cauchy-complete Rel(C,J)-categories, where Rel(C,J) is a suitable category of relations. We give a different, purely syntactical, proof of the equivalence passing through a generalization of the associate sheaf functor theorem.