Bicategories of Diffeological Groupoids

We study three variants of bicategories of diffeological groupoids, and show that they are all equivalent: the bicategory with generalised morphisms, the bicategory with anafunctors, and the bicategory with bibundles. Moreover, we show that the corresponding sub-bicategories of locally subductive diffeological groupoids, as well as Lie groupoids, are (essentially) full sub-bicategories. As applications, we obtain equivalences with the corresponding 2-categories of geometric stacks, and present some Morita invariants.Comment: 84 pages; v2 is essentially the same as v1 with some small modifications to the introduction and typographical correction