Model Riemannian Manifolds
Before we delve into the general theory of Riemannian manifolds, we pause to give it some substance by introducing a variety of “model Riemannian manifolds” that should help to motivate the general theory. These manifolds are distinguished by having a high degree of symmetry. We begin by describing the most symmetric model spaces of all—Euclidean spaces, spheres, and hyperbolic spaces. Then we explore some more general classes of Riemannian manifolds with symmetry.