Existence of Symplectic Structures on Torus Bundles Over Surfaces

Let E be the total space of a locally trivial torus bundle over a surface Σ_g of genus g > 1. Using Seiberg–Witten theory and spectral sequences, we prove that E carries a symplectic structure if and only if the homology class of the fiber [T²] is nonzero in H₂(E, ℝ). Mathematics Subject Classifications (2000): 53D05, 57R57, 55R20.     

On the Exceptional Principal Bundles Over a Surface

Let G be a simple simply connected complex Lie group. Some criteriaare given for the nonexistence of exceptional principal G-bundlesover a complex projective surface. As an application, it isshown that there are no exceptional G-bundles over a surfacewhose arithmetic genus is zero or one. It is also shown thatthere are no stable exceptional G-bundles over an abelian surface.2000 Mathematics Subject Classification 32L20, 14J60.     

Vector Bundles on Certain Non-algebraic Surfaces

It is well-known that every holomorphic vector bundle is filtrable on a projective algebraic     

Complete Sets of Relations in the Cohomology Rings of Moduli Spaces of Holomorphic Bundles and Parabolic Bundles Over a Riemann Surface

The cohomology ring of the moduli space of stable holomorphicvector bundles of rank n and degree d over a Riemann surfaceof genus g > 1 has a standard set of generators when n andd are coprime. When n = 2 the relations between these generatorsare well understood, and in particular a conjecture of Mumford,that a certain set of relations is a complete set, is knownto be true. In this article generalisations are given of Mumford'srelations to the cases when n > 2 and also when the bundlesare parabolic bundles, and these are shown to form completesets of relations. 2000 Mathematics Subject Classification 14H60.     

一类Hopf曲面上的全纯线丛的上同调

Let X be a non-primary Hopf Surface with Abelian fundamental groupπ_1 (X)(?) Z(?)Z_m, L a line bundle on X, we give a formula for computing the dimension of cohomology H~q(X,Ω~P(L)) and the explicit results for non-primary exceptional Hopf surface.     

Equivariant Vector Bundles Over Quantum Projective Spaces

Theoretical and Mathematical Physics - We construct equivariant vector bundles over quantum projective spaces using parabolic Verma modules over the quantum general linear group. Using an...     

The Pontryagin Rings of Moduli Spaces of Arbitrary Rank Holomorphic Bundles Over a Riemann Surface

The cohomology of M(n, d), the moduli space of stable holomorphicbundles of coprime rank n and degree d and fixed determinant,over a Riemann surface of genus g 2, has been widely studiedfrom a wide range of approaches. Narasimhan and Seshadri [17]originally showed that the topology of M(n, d) depends onlyon the genus g rather than the complex structure of . An inductivemethod to determine the Betti numbers of M(n, d) was first givenby Harder and Narasimhan [7] and subsequently by Atiyah andBott [1]. The integral cohomology of M(n, d) is known to haveno torsion [1] and a set of generators was found by Newstead[19] for n = 2, and by Atiyah and Bott [1] for arbitrary n.Much progress has been made recently in determining the relationsthat hold amongst these generators, particularly in the ranktwo, odd degree case which is now largely understood. A setof relations due to Mumford in the rational cohomology ringof M(2, 1) is now known to be complete [14]; recently severalauthors have found a minimal complete set of relations for the‘invariant’ subring of the rational cohomology ofM(2, 1) [2, 13, 20, 25]. Unless otherwise stated all cohomology in this paper will haverational coefficients.     

On Holomorphic Principal Bundles Over a Compact Riemann Surface Admitting a Flat Connection, II

Holomorphic principal bundles over a compact Riemann surfaceX that admits a flat connection are considered. A holomorphicG-bundle over X, where G is a connected semisimple linear algebraicgroup over C, admits a flat connection if and only if the adjointvector bundle admits one. More generally, for a complex reductivegroup G, the necessary and sufficient condition on a G-bundleto admit a flat connection is described. This simplifies thecriterion obtained by the authors and given in Math. Ann. 322(2002) 333–346. 2000 Mathematics Subject Classification53C05, 32L05.     

Circle and Line Bundles Over Generalized Weyl Algebras

Strongly \(\mathbb {Z}\)-graded algebras or principal circle bundles and associated line bundles or invertible bimodules over a class of generalized Weyl algebras \({\mathcal B}(p;q,0)\) (over a ring of polynomials in one variable) are constructed. The Chern-Connes pairing between the cyclic cohomology of \({\mathcal B}(p;q,0)\) and the isomorphism classes of sections of associated line bundles over \({\mathcal B}(p;q,0)\) is computed, thus demonstrating that these bundles, which are labelled by integers, are non-trivial and mutually non-isomorphic. The constructed strongly \(\mathbb {Z}\)-graded algebras are shown to have Hochschild cohomology reminiscent of that of Calabi-Yau algebras. The paper is supplemented by an observation that a grading by an Abelian group in the middle of a short exact sequence is strong if and only if the induced gradings by the outer groups in the sequence are strong.     

Surface Bundles with Nonvanishing Signature

Using the theory of Lefschetz fibrations and recent advances in mapping class group theory, surface bundles over surfaces with nonzero signature and small base genus are constructed. In particular, a genus-5 fibration over the surface of genus 26 with nonzero signature is given –- improving former results on the possible base genera for surface bundles over surfaces with nonzero signature.     

一类第一 Betti数为奇数的曲面上的向量丛

本文得到一些有关一类第一Betti数为奇数的曲面上的全纯向量丛的结果,以及例外Hopf曲面上的集合IS2(X,0)的描述．     

Rank 2 Ample Vector Bundles on Some Smooth Rational Surfaces

Several classification results for ample vector bundles of rank 2 on Hirzebruch surfaces, and on Del Pezzo surfaces, are obtained. In particular, we classify rank 2 ample vector bundles with _c2 less than seven on Hirzebruch surfaces, and with _c2 less than four on Del Pezzo surfaces.     

On Some Moduli Spaces of Bundles on K3 Surfaces

We give infinitely many examples in which the moduli space of rank 2 H-stable sheaves on a K3 surface S endowed by a polarization H of degree 2g – 2, with Chern classes c₁ = H and c₂ = g – 1, is birationally equivalent to the Hilbert scheme S[g – 4] of zero dimensional subschemes of S of length g – 4. We get in this way a partial generalization of results from [5] and [1].     

On Some Moduli Spaces of Bundles on K3 Surfaces

We give infinitely many examples in which the moduli space of rank 2 H-stable sheaves on a K3 surface S endowed by a polarization H of degree 2g – 2, with Chern classes c₁ = H and c₂ = g – 1, is birationally equivalent to the Hilbert scheme S[g – 4] of zero dimensional subschemes of S of length g – 4. We get in this way a partial generalization of results from [5] and [1].     

Spectra of Unit Tangent Bundles of Compact Hyperbolic Riemann Surfaces

Recent results of Gordon, Mao and Pesce imply that isospectral compact hyperbolic Riemann surfaces have Laplace and length isospectral unit tangent bundles. In this note we give explicit formulae relating the spectra of such surfaces and those of their unit tangent bundles, and use them to prove the converses.     

Generalized Adjunction of k-Very Ample Vector Bundles on Algebraic Surfaces

We study the k-very ampleness of the adjoint bundle K _S+det E associated to a k-very ample vector bundle E on an algebraic surface S. We extend the results of Beltrametti and Sommese to the vector bundle case and give the classification of the pairs (S, E) such that the preservation of k-very ampleness fails.     

Some Results on Holomorphic Vector Bundles Over General Hopf Manifolds

1 Introduction In recent years, holomorphic vector bundles on non-algebraic manifolds received increased attention. The main problem is to determine which continuous complex vector bundle carries a holomorphic structure or furthermore a holomorphic filtrable structure. D. Mall studied vector bundles on the primary Hopf manifolds。