Every diffeological space is naturally stratified by the action of its diffeomorphisms: the Klein Stratification. In this talk, I will introduce the basics of diffeology and explain how it provides a natural framework for understanding singular spaces. I will then describe the Klein stratification for (diffeological) orbifolds, situating it within the broader context of formal and geometric stratifications in diffeology. This perspective allows us to analyze quotient spaces, group actions, and singular structures in a unified and flexible manner.
Johannes Kellendonk
