DSpace Collection:http://www.openstarts.units.it:80/dspace/handle/10077/43152015-09-25T02:25:28Z2015-09-25T02:25:28ZIrreducible unitary representations of a diffeomorphisms group of an infinite-dimensional real manifoldLüdkovsky, S.V.http://www.openstarts.units.it:80/dspace/handle/10077/43622012-11-23T10:53:26Z1999-01-01T00:00:00ZTitle: Irreducible unitary representations of a diffeomorphisms group of an infinite-dimensional real manifold
Authors: Lüdkovsky, S.V.
Abstract: Groups of diffeomorphisms $Diff_{\beta,\Upsilon}^{t}$ (M) of infinite-dimensionai
real Banach manifolds M are defined. Their structure is studied. Irreducible
unitary representations of a group of diffeomorphisms associated with
quasi-invariant measures on a Banach manifold are constructed.
Type: Articolo1999-01-01T00:00:00ZDetermination of convex bodies from $\pm \infty$-chord functionsSoranzo, Alessandrohttp://www.openstarts.units.it:80/dspace/handle/10077/43612012-11-23T10:50:05Z1999-01-01T00:00:00ZTitle: Determination of convex bodies from $\pm \infty$-chord functions
Authors: Soranzo, Alessandro
Abstract: We generalize the concept of i-chord function to the cases $i=+\infty$
and $i=-\infty$, and we extend two results concerning the determination
of convex bodies from i-chord functions to those new values of i.
Type: Articolo1999-01-01T00:00:00ZTwistor Bundles of Almost Symplectic ManifoldsNannicini, Antonellahttp://www.openstarts.units.it:80/dspace/handle/10077/43602012-11-23T11:23:43Z1999-01-01T00:00:00ZTitle: Twistor Bundles of Almost Symplectic Manifolds
Authors: Nannicini, Antonella
Abstract: In this paper we introduce the twistor bundle of a 2n-dimensional
almost symplectic manifold M as the quotient bundle $\frac{P\left(M,Sp\left(2n\right)\right)}{U\left(n\right)}$.
Given a symplectic connection on M we introduce a natural almost Hermitian
structure on the twistor bundle and we prove that this structure is
K$\ddot{\textrm{a}}$hler if and only if M is symplectic and the chosen
connection has vanishing curvature and (0,2)-part of the torsion.
Moreover we prove that in the case of $\mathbb{R}^{2n}$ with standard
symplectic structure the twistor bundle turns out to be K$\ddot{\textrm{a}}$hler
with constant scalar curvature for a certain class of symplectic connections.
Type: Articolo1999-01-01T00:00:00ZTotally geodesic horizontally conformal mapsMustafa, M.T.http://www.openstarts.units.it:80/dspace/handle/10077/43592012-11-23T11:17:25Z1999-01-01T00:00:00ZTitle: Totally geodesic horizontally conformal maps
Authors: Mustafa, M.T.
Abstract: We obtain a characterization of totally geodesic horizontally conformal
maps by a method which arises as a consequence of the Bochner technique
for harmonic morphisms. As a geometric consequence we show that the
existence of a non-constant harmonic morphism $\textrm{Ø}$ from a
compact Riemannian manifold M$^{m}$ of non-negative Ricci curvature
to a compact Riemannian manifold of non-positive scalar curvature,
forces M$^{m}$ either to be a global Riemannian product of integral
manifolds of vertical and horizontal distributions or to be covered
by a global Riemannian product.
Type: Articolo1999-01-01T00:00:00Z