Results 21 to 30 of about 2,119 (92)
Quantum cosmological Friedman models with a Yang-Mills field and positive energy levels
, 2010 We prove the existence of a spectral resolution of the Wheeler-DeWitt equation when the matter field is provided by a Yang-Mills field, with or without mass term, if the spatial geometry of the underlying spacetime is homothetic to $\R[3]$.
Claus Gerhardt +3 more
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Estimates for the volume of a Lorentzian manifold
, 2002 We prove new estimates for the volume of a Lorentzian manifold and show especially that cosmological spacetimes with crushing singularities have finite volume.Comment: 8 pages, a pdf version of the preprint can also be retrieved from http://www.math ...
C. Gerhardt +5 more
core +3 more sources
Osculating curves in 4-dimensional semi-Euclidean space with index 2
Open Mathematics, 2017 In this paper, we give the necessary and sufficient conditions for non-null curves with non-null normals in 4-dimensional Semi-Euclidian space with indeks 2 to be osculating curves.
İlarslan Kazim +2 more
doaj +1 more source
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.
core +1 more source
On a Class Almost Contact Manifolds with Norden Metric [PDF]
, 2010 Certain curvature properties and scalar invariants of the manifolds belonging to one of the main classes almost contact manifolds with Norden metric are considered.
Teofilova, Marta
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Null scrolls with prescribed curvatures in Lorentz-Minkowski 3-space
Analele Stiintifice ale Universitatii Ovidius Constanta: Seria Matematica, 2020 In Lorentz-Minkowski 3-space, null scrolls are ruled surfaces with a null base curve and null rulings. Their mean, as well as their Gaussian curvature, depends only on a parameter of a base curve. In the present paper, we obtain the first-order nonlinear
Šipuš Željka Milin +2 more
doaj +1 more source
Dependence of the Gauss-Codazzi equations and the Ricci equation of Lorentz surfaces [PDF]
, 2013 The fundamental equations of Gauss, Codazzi and Ricci provide the conditions for local isometric embeddability. In general, the three fundamental equations are independent for surfaces in Riemannian 4-manifolds. In contrast, we prove in this article that
Chen, Bang-Yen
core
Curvature estimates for Weingarten hypersurfaces in Riemannian manifolds
, 2008 We prove curvature estimates for general curvature functions. As an application we show the existence of closed, strictly convex hypersurfaces with prescribed curvature $F$, where the defining cone of $F$ is $\C_+$.
Ball J. M. +3 more
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The existence of light-like homogeneous geodesics in homogeneous Lorentzian manifolds
, 2012 In previous papers, a fundamental affine method for studying homogeneous geodesics was developed. Using this method and elementary differential topology it was proved that any homogeneous affine manifold and in particular any homogeneous pseudo ...
Calvaruso +10 more
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Parallal Spinors on Pseudo-Riemannian SpinC Manifolds [PDF]
J.Geom.Phys. 56 (2006) 1473-1483, 2005 We describe, by their holonomy groups, all simply connected irreducible non-locally symmetric pseudo-Riemannian SpinC manifolds which admit parallel spinors. So we generalise the Riemannian case and the pseudo-Riemannian one.
arxiv +1 more source