Removability of singularities of harmonic maps into pseudo-riemannian manifolds
Résultats nouveaux a propos des conjectures de Lichnerowicz et de Carathéodory
Ricci-flat left-invariant Lorentzian metrics on 2-step nilpotent Lie groups
The purpose of this paper is to investigate Ricci-flatness of left-invariant Lorentzian metrics on 2-step nilpotent Lie groups. We first show that if is a Ricci-flat left-invariant Lorentzian metric on a 2-step nilpotent Lie group , then the restriction of to the center of the Lie algebra of is degenerate. We then characterize the 2-step nilpotent Lie groups which can be endowed with a Ricci-flat left-invariant Lorentzian metric, and we deduce from this that a Heisenberg Lie group can be...
Ruled surfaces in Lorentz-Minkowski 3-spaces with non-degenerate second fundamental form.
-metrische Zusammenhänge in isotropen Mannigfaltigkeiten. (- metric connections in isotropic manifolds).
S1-equivariant Minimal Tori in S4 and S1-equivariant Willmore Tori in S3.
Schémas d'Einstein-Dirac en spin 1/2 et généralisations
Screen conformal half-lightlike submanifolds.
Screen transversal lightlike submanifolds of indefinite Sasakian manifolds.
Self-duality and pointwise Osserman manifolds
This paper is a contribution to the mathematical modelling of the hump effect. We present a mathematical study (existence, homogenization) of a Hamilton-Jacobi problem which represents the propagation of a front flame in a striated media.
Semi-invariant submanifolds of a Lorentzian para-Sasakian manifold.
Semi-parallel Lightlike Hypersurfaces of Indefinite Cosymplectic Space Forms
Semi-symmetric four dimensional neutral Lie groups
The present paper is concerned with obtaining a classification regarding to four-dimensional semi-symmetric neutral Lie groups. Moreover, we discuss some geometric properties of these spaces. We exhibit a rich class of non-Einstein Ricci soliton examples.
Slant lightlike submanifolds of indefinite Hermitian manifolds.
Some applications of Cartain's theory on three-dimensional Cauchy-Riemann geometry.
Some indefinite metrics and covariant derivatives of their curvature tensors
Some Para-Hermitian Related Complex Structures and Non-existence of Semi-Riemannian Metric on Some Spheres
It is shown that the spheres S^(2n) (resp: S^k with k ≡ 1 mod 4) can be given neither an indefinite metric of any signature (resp: of signature (r, k − r) with 2 ≤ r ≤ k − 2) nor an almost paracomplex structure. Further for every given Riemannian metric on an almost para-Hermitian manifold with the associated 2-form φ one can construct an almost Hermitian structure (under certain conditions, two different almost Hermitian structures) whose associated 2-form(s) is φ.
Some results on the existence of geodesics in static Lorentz manifolds with singular boundary
In this Note we deal with the problem of the existence of geodesies joining two given points of certain non-complete Lorentz manifolds, of which the Schwarzschild spacetime is the simplest physical example.
Some results on trans-Sasakian manifolds
Some rigidity results for spatially closed spacetimes