We study analogues of the notions from Lie theory of Levi subgroup and Levi decomposition, in the case of groups G definable in an ominimal expansion of a real closed field. With suitable definitions, we prove that G has a unique maximal ind-definable semisimple subgroup S, up to conjugacy, and that G = R ·S where R is the solvable radical of G. We also prove that any semisimple subalgebra of t...

We propose a unified normal form for all Levi-nondegenerate hypersurface type almost CR structures.

We start from the pure Einstein-Hilbert action S = λ 2 R ⋆ 1 in Metric-Affine-Gravity, with the orthonormal metric g ab = η ab. We get an effective Levi-Civita Dilaton gravity theory in which the Dilaton field is related to the scaling of the gravitational coupling. When the Weyl symmetry is broken the resulting Einstein-Hilbert term is equivalent to the Levi-Civita one, using the projective in...

This paper is devoted to compute the energy-momentum densities for two exact solutions of the Einstein field equations by using the prescriptions of Einstein, Landau-Lifshitz, Papapetrou and Möller. The spacetimes under consideration are the Weyl-Lewis-Papapetrou and the Levi-Civita metrics. The Weyl metric becomes the special case of the Weyl-Lewis-Papapetrou solution. The Levi-Civita metric p...

Is a complex space X which is the union of an increasing sequence X1 ⊂ X2 ⊂ X3 ⊂ · · · of open Stein subspaces itself a Stein space ? From the begining this question has held great interest in Stein theory. The special case when {Xj}j≥1 is a sequence of Stein domains in I C n had been proved long time ago by Behnke and Stein [2]. In 1956, Stein [13] answered positively the question under the ad...

The first part of this paper considers higher order CR invariants of three dimensional hypersurfaces of finite type. Using a full normal form we give a complete characterization of hypersurfaces with trivial local automorphism group, and analogous results for finite groups. The second part considers hypersurfaces of finite Catlin multitype, and the Kohn-Nirenberg phenomenon in higher dimensions...

We prove the existence of a local smooth Levi decomposition for smooth Poisson structures and Lie algebroids near a singular point.

‎In this paper we try to extend geometric concepts in the context of operator valued tensors‎. ‎To this end‎, ‎we aim to replace the field of scalars $ mathbb{R} $ by self-adjoint elements of a commutative $ C^star $-algebra‎, ‎and reach an appropriate generalization of geometrical concepts on manifolds‎. ‎First‎, ‎we put forward the concept of operator-valued tensors and extend semi-Riemannian...

En su segundo libro, La tregua (1963), Primo Levi relata las peripecias de regreso desde Auschwitz a Turín: un largo peregrinaje que duró ocho meses obligándole cruzar Europa, y sobre todo Rusia, en todas direcciones. El artículo aborda los significados histórico, político, etimológico psicológico la palabra «tregua», simetrías contrastes dentro obra (además algunas con primera Levi, Se questo ...