Rigidity of an Isometric -Action
arXiv:1603.01577
Abstract
We characterize the universal covering of connected analytic pseudo-Riemannian manifolds which admit a non-trivial and isometric action of the simple Lie group with a dense orbit preserving a finite volume. If such manifold is also weakly irreducible we prove that is isometric to, or a quotient space of, a simple Lie group containing .