A famous theorem of Hsiang and Kleiner states that if S^1 acts on a positively curved 4-dimensional manifold, then the manifold is homeomorphic to either S^4, RP^4 or CP^2. In this talk we will talk about a possible generalization to the orbifold case, and discuss several interesting examples.
Graduate Student Geometry-Topology Seminar
Wednesday, October 16, 2013 - 10:00am
Dmytro Yeroshkin
University of Pennsylvania