Abstract
Let (M, Q) be an n-dimensional connected Riemannian manifold and 1 ≦ k ≦ n. Then (M, Q) is called k-fold symmetric if given any k tangent vectors ξ1, ξ2, … , ξk at a point x ∈ M, there exists an isometry σ such that σ(x) = x and dσ(ξi) = −ξi, i = 1, 2, … , k. This kind of manifolds with k = 1, usually called weakly symmetric Riemannian manifolds, was introduced by A. Selberg as a weakening of the notion of n-fold symmetric ones, i.e., globally symmetric Riemannian manifolds. It is well known that there are many more weakly symmetric spaces than globally symmetric ones. In this paper, we prove that a connected simply connected 2-fold symmetric Riemannian manifold must be globally symmetric.
©[2013] by Walter de Gruyter Berlin Boston
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Articles in the same Issue
- Homological mirror symmetry for toric orbifolds of toric del Pezzo surfaces
- On nonary cubic forms: IV
- Convexity estimates for level sets of quasiconcave solutions to fully nonlinear elliptic equations
- Inhomogeneous cubic congruences and rational points on del Pezzo surfaces
- A reduction theorem for the Alperin–McKay conjecture
- Regularity of solutions to the parabolic fractional obstacle problem
- On the symmetry of Riemannian manifolds