Strictly non-proportional geodesically equivalent metrics have h top ( g ) = 0
نویسندگان
چکیده
منابع مشابه
Splitting and gluing constructions for geodesically equivalent pseudo-Riemannian metrics
Two metrics g and ḡ are geodesically equivalent, if they share the same (unparameterized) geodesics. We introduce two constructions that allow one to reduce many natural problems related to geodesically equivalent metrics, such as the classification of local normal forms and the Lie problem (the description of projective vector fields), to the case when the (1, 1)−tensor Gj := g ik ḡkj has one ...
متن کاملSplitting and Gluing Lemmas for Geodesically Equivalent Pseudo-riemannian Metrics
Two metrics g and ḡ are geodesically equivalent if they share the same (unparameterized) geodesics. We introduce two constructions that allow one to reduce many natural problems related to geodesically equivalent metrics, such as the classification of local normal forms and the Lie problem (the description of projective vector fields), to the case when the (1, 1)−tensor Gj := g ik ḡkj has one r...
متن کامل1 0 Ju n 20 08 Geodesically complete Lorentzian metrics on some homogeneous 3 manifolds
We show that a necessary condition for the completeness of the geodesics of left invariant pseudo-Riemannian metrics on Lie groups is also sufficient in the case of 3-dimensional unimodular Lie groups, and not sufficient for 3-dimensional non-unimodular Lie groups. As a consequence it is possible to identify, amongst the compact locally homogeneous Lorentz 3-manifolds with non compact (local) i...
متن کاملGeodesically Complete Lorentzian Metrics on Some Homogeneous 3 Manifolds
In this work it is shown that a necessary condition for the completeness of the geodesics of left invariant pseudo-Riemannian metrics on Lie groups is also sufficient in the case of 3-dimensional unimodular Lie groups, and not sufficient for 3-dimensional non unimodular Lie groups. As a consequence it is possible to identify, amongst the compact locally homogeneous Lorentzian 3-manifolds with n...
متن کاملCocompact Cat(0) Spaces Are Almost Geodesically Complete
Let M be a Hadamard manifold, that is, a complete simply connected riemannian manifold with non-positive sectional curvatures. Then every geodesic segment α : [0, a] → M from α(0) to α(a) can be extended to a geodesic ray α : [0,∞) → M . We say then that the Hadamard manifold M is geodesically complete. Note that, in this case, all geodesic rays are proper maps. CAT(0) spaces are generalization...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Ergodic Theory and Dynamical Systems
سال: 2006
ISSN: 0143-3857,1469-4417
DOI: 10.1017/s0143385705000283