Dmytro Yeroshkin
Abstract: We prove an analogue of the result of Hsiang and Kleiner for 4-dimensional compact orbifolds with positive curvature and an isometric circle action. Additionally, we prove that when the underlying space is simply connected, then the orbifold fundamental group provides a bound on the failure of integer-valued Poincare Duality of the underlying space, and if the orbifold is simply connected, then integer-valued Poincare Duality holds for the underlying space.
ArXiv: 1411.1700