We define a quantum generalization of the algebra of functions over an associated vector bundle of a principal bundle. Here the role of a quantum principal bundle is played by a Hopf-Galois extension. Smash products of an algebra times a Hopf algebra H are particular instances of these extensions, and in these cases we are able to define a differential calculus over their associated vector bund...

Smooth complex surfaces polarized with an ample and globally generated line bundle of degree three and four, such that the adjoint bundle is not globally generated, are considered. Scrolls of a vector bundle over a smooth curve are shown to be the only examples in degree three. Two classes of examples in degree four are presented, one of which is shown to characterize regular such pairs. A Reid...

Here’s the game plan: in Section 2 we’ll examine some properties of smooth 8-manifolds. Then in Section 3 we shall consider the disk bundle of a certain vector bundle (to be constructed in Section 4), the total space of which has boundary homeomorphic to the 7-sphere. Assuming it’s in fact diffeomorphic, we can construct a smooth 8-manifold from the disk bundle that fails to support the propert...

We study the existence of a natural ‘linearisation’ process for generalised connections on an affine bundle. It is shown that this leads to an affine generalised connection over a prolonged bundle, which is the analogue of what is called a connection of Berwald type in the standard theory of connections. Various new insights are being obtained in the fine structure of affine bundles over an anc...

On a smooth manifold M, the vector bundle structures of the second order tangent bundle, T M bijectively correspond to linear connections. In this paper we classify such structures for those Fréchet manifolds which can be considered as projective limits of Banach manifolds. We investigate also the relation between ordinary differential equations on Fréchet spaces and the linear connections on t...

In this note, we show that the holonomy group of a Riemannian connection on a k-dimensional Euclidean vector bundle is transitive on the unit sphere bundle whenever the Euler class χ is spherical. We extract several consequences from this, among them that this is always the case as long as χ does not vanish, and the base of the bundle is simply connected and rationally (k + 1)/2-connected.

We prove that a Finsler manifold Fm is of constant curvature K = 1 if and only if the unit horizontal Liouville vector field is a Killing vector field on the indicatrix bundle IM of Fm.

We prove a conjecture by F. Ferrari. Let X be the total space of a nonlinear deformation of a rank 2 holomorphic vector bundle on a smooth rational curve, such that X has trivial canonical bundle and has sections. Then the normal bundle to such sections is computed in terms of the rank of the Hessian of a suitably defined superpotential at its critical points. MSC: 14D15, 14H45, 83E30 PACS: 02....

We show that the tangent bundle of a projective manifold with nef anticanonical class is generically nef. That is, its restriction to curve cut out by general sufficiently ample divisors vector bundle. This confirms conjecture Peternell. As consequence, second Chern such has non-negative intersections divisors. also investigate under which conditions these positivities are strict, and answer qu...