Sur les Groupes Hyperboliques d’après Mikhael Gromov

轨形

拓扑学与几何学中，轨形（orbifold，“有轨的流形”）是对流形的推广. 粗略地说，轨形是局部为欧氏空间的有限群商的拓扑空间.

Orbifold

In the mathematical disciplines of topology and geometry, an orbifold (for "orbit-manifold") is a generalization of a manifold.