Tags: #higher-algebra/stacks #AG Refs: https://www.math.colostate.edu/~renzo/teaching/Orbifolds/Ruan.pdf Links: isotropy group global homotopy theory stacks MOC orbifold fundamental group crepant resolution deformation Thom form orbifold fundamental group Chern-Ruan theory stringy topology Bredon cohomology equivariant K theory Twisted K theory quantum cohomology elliptic complex Gromov-Witten invariants