Homogeneous C R-manifolds.
We point out relations between Siciak’s homogeneous extremal function and the Cauchy-Poisson transform in case is a ball in ℝ². In particular, we find effective formulas for for an important class of balls. These formulas imply that, in general, is not a norm in ℂ².
We recall first Mather's Lemma providing effective necessary and sufficient conditions for a connected submanifold to be contained in an orbit. We show that two homogeneous polynomials having isomorphic Milnor algebras are right-equivalent.
Un sous-ensemble pfaffien d’un ouvert semi-analytique est une intersection finie d’ensembles semi-analytiques relativement compacts de et de feuilles non spiralantes de certains feuilletages analytiques de codimension 1 de Les sous-ensembles semi-pfaffiens de sont les éléments de la plus petite classe de sous-ensembles de contenant les sous-ensembles pfaffiens de , stable par intersection finie, réunion finie et différence symétrique. Les ensembles -pfaffiens sont les éléments de la...
Homology with values in a connection with possibly irregular singular points on an algebraic curve is defined, generalizing homology with values in the underlying local system for a connection with regular singular points. Integration defines a perfect pairing between de Rham cohomology with values in the connection and homology with values in the dual connection.
Given an origami (square-tiled surface) with automorphism group , we compute the decomposition of the first homology group of into isotypic -submodules. Through the action of the affine group of on the homology group, we deduce some consequences for the multiplicities of the Lyapunov exponents of the Kontsevich-Zorich cocycle. We also construct and study several families of interesting origamis illustrating our results.
Given a Hörmander system on a domain we show that any subelliptic harmonic morphism from into a -dimensional riemannian manifold is a (smooth) subelliptic harmonic map (in the sense of J. Jost & C-J. Xu, [9]). Also is a submersion provided that and has rank . If (the Heisenberg group) and , where is the Lewy operator, then a smooth map is a subelliptic harmonic morphism if and only if is a harmonic morphism, where is the canonical circle bundle and is the Fefferman...