manifold
131Collapsing manifold — For the concept in homotopy, see collapse (topology). In Riemannian geometry, a collapsing or collapsed manifold is an n dimensional manifold M that admits a sequence of Riemannian metrics gn, such that as n goes to infinity the manifold is close …
132Spherical 3-manifold — In mathematics, a spherical 3 manifold M is a 3 manifold of the form M = S3 / Γ where Γ is a finite subgroup of SO(4) acting freely by rotations on the 3 sphere S3. All such manifolds are prime, orientable, and closed. Spherical 3 manifolds are… …
