Least-volume representatives of homology classes in
Leaves of foliations with a transverse geometric structure of finite type.
In this short note we find some conditions which ensure that a G foliation of finite type with all leaves compact is a Riemannian foliation of equivalently the space of leaves of such a foliation is a Satake manifold. A particular attention is paid to transversaly affine foliations. We present several conditions which ensure completeness of such foliations.
Lectures on generalized complex geometry and supersymmetry
These are the lecture notes from the 26th Winter School “Geometry and Physics", Czech Republic, Srní, January 14 – 21, 2006. These lectures are an introduction into the realm of generalized geometry based on the tangent plus the cotangent bundle. In particular we discuss the relation of this geometry to physics, namely to two-dimensional field theories. We explain in detail the relation between generalized complex geometry and supersymmetry. We briefly review the generalized Kähler and generalized...
Lefschetz coincidence numbers of solvmanifolds with Mostow conditions
For any two continuous maps , between two solvmanifolds of the same dimension satisfying the Mostow condition, we give a technique of computation of the Lefschetz coincidence number of , . This result is an extension of the result of Ha, Lee and Penninckx for completely solvable case.
Lefschetz fibrations and the Hodge bundle.
Lefschetz fibrations, complex structures and Seifert fibrations on .
Lefschetz fibrations in symplectic geometry.
Left-invariant almost complex structures and the associated metrics on four-dimensional direct products of Lie groups.
Legendrian dual surfaces in hyperbolic 3-space
We consider surfaces in hyperbolic 3-space and their duals. We study flat dual surfaces in hyperbolic 3-space by using extended Legendrian dualities between pseudo-hyperspheres in Lorentz-Minkowski 4-space. We define the flatness of a surface in hyperbolic 3-space by the degeneracy of its dual, which is similar to the case of the Gauss map of a surface in Euclidean 3-space. Such surfaces are a kind of ruled surfaces. Moreover, we investigate the singularities of these surfaces and the dualities...
Legendrian foliations on almost -manifolds.
Lemme de Moser feuilleté et clasifications des variétés de Poisson régulières.
Regular Poisson structures with fixed characteristic foliation F are described by means of foliated symplectic forms. Associated to each of these structures, there is a class in the second group of foliated cohomology H2(F). Using a foliated version of Moser's lemma, we study the isotopy classes of these structures in relation with their cohomology class. Explicit examples, with dim F = 2, are described.
Length of curves on Lip manifolds
In this paper the length of a curve on a Lipschitz Riemannian manifold is defined. It is shown that the above definition is consistent with the definition of the geodesic distance already introduced by the authors, both in a geometrical and analytical way.
Length spectrum for compact locally symmetric spaces of strictly negative curvature
Length spectrum invariants of Riemannian manifolds.
L'entropie minimale des espaces symétriques
L'équation de la chaleur associée à la courbure de Ricci
Les connexions hypergéométriques et le théorème de linéarité de T. Terasoma
Cet article a pour but de calculer les coefficients du caractère du produit alterné des déterminants des connexions de Gauss–Manin associées à une famille de polynômes sur . Nous généralisons et précisons certains résultats de T. Terasoma (Inv. Math., 1992). L’idée de ce travail est de considérer la structure mixte donnée par l’action des translations entières sur les exposants sur le déterminant de l’image directe de et celle de -module.
Les espaces de König du point de vue des espaces fibrés à connexion
Les géométries de Hilbert sont à géométrie locale bornée
On montre que la géométrie de Hilbert d’un domaine convexe de est à géométrie locale bornée c-à-d que pour un rayon fixé, toutes les boules sont bilipschitz à un domaine de euclidien. On en déduit que si la géométrie de Hilbert est hyperbolique au sens de Gromov, alors le bas de son spectre est strictement positif. On donne un contre-exemple en dimension trois qui montre que la réciproque n’est pas vraie pour les géométries de Hilbert non planes.
Les groupes de Burger-Mozes ne sont pas kählériens
Burger et Mozes ont construit des exemples de groupes simples infinis, qui sont des réseaux dans le groupe des automorphismes d’un immeuble cubique. On montre qu’il n’existe pas de morphisme d’un groupe kählérien vers l’un de ces groupes dont le noyau soit finiment engendré. On en déduit que ces groupes ne sont pas kählériens.