Semi-martingales dans les espaces homogènes
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.
Locally exact complexes of invariant differential operators are constructed on the homogeneous model for a parabolic geometry for the even orthogonal group. The tool used for the construction is the Penrose transform developed by R. Baston and M. Eastwood. Complexes constructed here belong to the singular infinitesimal character.
Using the exact representation of Carnot-Carathéodory balls in the Heisenberg group, we prove that: 1. in the classical sense for all with , where is the distance from the origin; 2. Metric balls are not optimal isoperimetric sets in the Heisenberg group.
Let Fr(n) be the incomplete complex flag manifold of length r in Cn. We make a start on the complete determination of the torsion part of the group KO-i(Fr(n)) giving results here when r = 2, 3.
We show that a bi-invariant metric on a compact connected Lie group is spectrally isolated within the class of left-invariant metrics. In fact, we prove that given a bi-invariant metric on there is a positive integer such that, within a neighborhood of in the class of left-invariant metrics of at most the same volume, is uniquely determined by the first distinct non-zero eigenvalues of its Laplacian (ignoring multiplicities). In the case where is simple, can be chosen to be two....
Nous passons en revue certains résultats récents sur l’existence et l’unicité des sphères à courbure moyenne constante dans les variétés riemanniennes homogènes simplement connexes de dimension et leurs liens avec le problème isopérimétrique dans ces variétés.
In his famous five variables paper Elie Cartan showed that one can canonically associate to a generic rank 2 distribution on a 5 dimensional manifold a Cartan geometry modeled on the homogeneous space , where is one of the maximal parabolic subgroups of the exceptional Lie group . In this article, we use the algebra of split octonions to give an explicit global description of the distribution corresponding to the homogeneous model.
We study the stability of the geodesic flow as a critical point for the energy functional when the base space is a compact orientable quotient of a two-point homogeneous space.
Some new examples of standard homogeneous Einstein manifolds with semisimple transitive groups of motions and semisimple isotropy subgroups are constructed. For the construction of these examples the solutions of some systems of Diophantine equations are used.
Structure of geodesic graphs in special families of invariant weakly symmetric Finsler metrics on modified H-type groups is investigated. Geodesic graphs on modified H-type groups with the center of dimension or are constructed. The new patterns of algebraic complexity of geodesic graphs are observed.