All a b c d e f g h i j k l m n o p q r s t u v w x y z Other

Previous Page 17 Next

Displaying 321 – 340 of 937

Showing per page

Harmonic morphisms between riemannian manifolds

Bent Fuglede (1978)

Annales de l'institut Fourier

A harmonic morphism f : M → N between Riemannian manifolds M and N is by definition a continuous mappings which pulls back harmonic functions. It is assumed that dim M ≥ dim N , since otherwise every harmonic morphism is constant. It is shown that a harmonic morphism is the same as a harmonic mapping in the sense of Eells and Sampson with the further property of being semiconformal, that is, a conformal submersion of the points where d f vanishes. Every non-constant harmonic morphism is shown to be an open mapping....

Harmonie reflections

Lieven Vanhecke, Maria-Elena Vazquez-Abal (1988)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

We study local reflections ϕ σ with respect to a curve σ in a Riemannian manifold and prove that σ is a geodesic if ϕ σ is a harmonic map. Moreover, we prove that the Riemannian manifold has constant curvature if and only if ϕ σ is harmonic for all geodesies σ .

High-order angles in almost-Riemannian geometry

Ugo Boscain, Mario Sigalotti (2006/2007)

Séminaire de théorie spectrale et géométrie

Let X and Y be two smooth vector fields on a two-dimensional manifold M . If X and Y are everywhere linearly independent, then they define a Riemannian metric on M (the metric for which they are orthonormal) and they give to M the structure of metric space. If X and Y become linearly dependent somewhere on M , then the corresponding Riemannian metric has singularities, but under generic conditions the metric structure is still well defined. Metric structures that can be defined locally in this way...

Homogeneous geodesics in a three-dimensional Lie group

Rosa Anna Marinosci (2002)

Commentationes Mathematicae Universitatis Carolinae

O. Kowalski and J. Szenthe [KS] proved that every homogeneous Riemannian manifold admits at least one homogeneous geodesic, i.eȯne geodesic which is an orbit of a one-parameter group of isometries. In [KNV] the related two problems were studied and a negative answer was given to both ones: (1) Let M = K / H be a homogeneous Riemannian manifold where K is the largest connected group of isometries and dim M ≥ 3 . Does M always admit more than one homogeneous geodesic? (2) Suppose that M = K / H admits m = dim M linearly independent...

Inégalité de Sobolev et volume asymptotique

Gilles Carron (2012)

Annales de la faculté des sciences de Toulouse Mathématiques

En 1999, M. Ledoux a démontré qu’une variété complète à courbure de Ricci positive ou nulle vérifiant une inégalité de Sobolev euclidienne était euclidienne. On présente un raccourci de la preuve. De plus nos arguments permettent un raffinement d’un résultat de B-L. Chen et X-P. Zhu à propos des variétés localement conformément plate à courbure de Ricci positive ou nulle. Enfin, on étudie ce qui se passe lorsque l’hypothèse sur la courbure de Ricci est remplacée par une hypothèse sur la courbure...

Currently displaying 321 – 340 of 937