Results 21 to 30 of about 1,290 (90)
A New Quasi-local Mass and Positivity [PDF]
, 2007 We use an idea of Wang and Yau to give a new definition of quasi-local mass for a topological sphere in an initial date set. The new definition modifies Brown-York's definition by using certain spinor norm as lapse function.
Zhang, Xiao
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Screen conformal half‐lightlike submanifolds
International Journal of Mathematics and Mathematical Sciences, Volume 2004, Issue 68, Page 3737-3753, 2004., 2004 We study some properties of a half‐lightlike submanifold M, of a semi‐Riemannian manifold, whose shape operator is conformal to the shape operator of its screen distribution. We show that any screen distribution S(TM) of M is integrable and the geometry of M has a close relation with the nondegenerate geometry of a leaf of S(TM).
K. L. Duggal, B. Sahin
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Trajectories under a vectorial potential on stationary manifolds
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 23, Page 1481-1495, 2003., 2003 By using variational methods, we study the existence and multiplicity of trajectories under a vectorial potential on (standard) stationary Lorentzian manifolds possibly with boundary.
Rossella Bartolo
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Ricci-flat and Einstein pseudoriemannian nilmanifolds
Complex Manifolds, 2019 This is partly an expository paper, where the authors’ work on pseudoriemannian Einstein metrics on nilpotent Lie groups is reviewed. A new criterion is given for the existence of a diagonal Einstein metric on a nice nilpotent Lie group.
Conti Diego, Rossi Federico A.
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Biharmonic curves in Minkowski 3‐space
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 21, Page 1365-1368, 2003., 2003 We give a differential geometric interpretation for the classification of biharmonic curves in semi‐Euclidean 3‐space due to Chen and Ishikawa (1991).
Jun-Ichi Inoguchi
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Chern‐Simons forms of pseudo‐Riemannian homogeneity on the oscillator group
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 47, Page 3007-3014, 2003., 2003 We consider forms of Chern‐Simons type associated to homogeneous pseudo‐Riemannian structures. The corresponding secondary classes are a measure of the lack of a homogeneous pseudo‐Riemannian space to be locally symmetric. In the present paper, we compute these forms for the oscillator group and the corresponding secondary classes of the compact ...
P. M. Gadea, J. A. Oubiña
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Pseudoinversion of degenerate metrics
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 55, Page 3479-3501, 2003., 2003 Let (M, g) be a smooth manifold M endowed with a metric g. A large class of differential operators in differential geometry is intrinsically defined by means of the dual metric g∗ on the dual bundle TM∗ of 1‐forms on M. If the metric g is (semi)‐Riemannian, the metric g∗ is just the inverse of g. This paper studies the definition of the above‐mentioned
C. Atindogbe, J.-P. Ezin, Joël Tossa
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Examples of naturally reductive pseudo-Riemannian Lie groups
, 2011 We provide examples of naturally reductive pseudo-Riemannian spaces, in particular an example of a naturally reductive pseudo-Riemannian 2-step nilpotent Lie group $(N, _N)$, such that $_N$ is invariant under a left action and for which the center is ...
Ovando, Gabriela P.
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A note on the existence of standard splittings for conformally stationary spacetimes
, 2012 Let $(M,g)$ be a spacetime which admits a complete timelike conformal Killing vector field $K$. We prove that $(M,g)$ splits globally as a standard conformastationary spacetime with respect to $K$ if and only if $(M,g)$ is distinguishing (and, thus ...
Beem J K +11 more
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Hypersurfaces in a conformally flat space with curvature collineation
International Journal of Mathematics and Mathematical Sciences, Volume 14, Issue 3, Page 595-604, 1991., 1990 We classify the shape operators of Einstein and pseudo Einstein hypersurfaces in a conformally flat space with a symmetry called curvature collineation. We solve the fundamental problem of finding all possible forms of non‐diagonalizable shape operators.
K. L. Duggal, R. Sharma
wiley +1 more source