Céline Roméro

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We discuss and prove a theorem which asserts that any n-dimensional semiRiemannian manifold can be locally embedded in a (n+1)-dimensional space with a non-degenerate Ricci tensor which is equal, up to a local analytic diffeomorphism, to the Ricci tensor of an arbitrary specified space. This may be regarded as a further extension of the Campbell-Magaard(More)
We discuss how embeddings in connection with the CampbellMagaard (CM) theorem can have a physical interpretation. We show that any embedding whose local existence is guaranteed by the CM theorem can be viewed as a result of the dynamical evolution of initial data given in a four-dimensional spacelike hypersurface. By using the CM theorem, we establish that(More)
In this extended work, a syntactic and semantic analysis of Urdu Modal verbs is presented using lexical functional grammar encoded in an environment of the XLE parser. This grammar is developed to understand the syntactic and semantic structure of Urdu modal verbs taken from the sentences of a corpus. Based on this analysis, Urdu modal verbs are finally(More)
As forest managers and owners must have precise assessments of sustainability, in this study we have proposed a methodology based on multi-criteria techniques for assessing sustainability in industrial forest plantations and establishing a ranking of these plantations in terms of sustainability. First, we identified and have briefly described a set of(More)
We consider global properties of gravitomagnetism by investigating the gravitomagnetic field of a rotating cosmic string. We show that although the gravitomagnetic field produced by such a configuration of matter vanishes locally, it can be detected globally. In this context we discuss the gravitational analogue of the Aharonov-Bohm effect. PACS: 04.20.Cv;(More)
We briefly review a few aspects of the development of differential geometry which may be considered as being influenced by Einstein ́s general relativity. We focus on how Einsteins’s quest for a complete geometrization of matter and electromagnetism gave rise to an enormous amount of theoretical work both on physics and mathematics. In connection with this(More)
We revisit the Riemann-Cartan geometry in the context of recent higher-dimensional theories of spacetime. After introducing the concept of torsion in a modern geometrical language we present some results that represent extensions of Riemannian theorems. We consider the theory of local embeddings and submanifolds in the context of Riemann-Cartan geometries(More)
Nowadays, the application of data mining techniques in e-learning and web based adaptive educational system is increasing exponentially. The discovered useful information can be used directly by the teacher or the author of the course to improve the instructional/learning performance. This can be an arduous task and therefore educational recommender systems(More)
According to the Campbell-Magaard theorem, any analytical spacetime can be locally and analytically embedded into a five-dimensional pseudo-Riemannian Ricci-flat manifold. We find explicitly this embedding for Gödel’s universe. The embedding space is Ricci-flat and has a non-Lorentzian signature of type (+ + − − −). We also show that the embedding found is(More)
We briefly revisit the Schwarzschild-de Sitter solution in the context of five-dimensional general relativity. We obtain a class of fivedimensional solutions of Einstein vacuum field equations into which the four-dimensional Schwarzschild-de Sitter space can be locally and isometrically embedded. We show that this class of solutions is well-behaved in the(More)