where the maximum is taken over all line subbundles L of E, is just the minimum of the self intersection numbers of all sections of the ruled surface P(E) â†’ C. Note that E is stable (respectivelyâ€¦ (More)

In this paper we obtain bounds on h(E) where E is a semistable bundle of rank 3 over a smooth irreducible projective curve X of genus g â‰¥ 2 defined over an algebraically closed field ofâ€¦ (More)

In a previous paper we showed that for every polarization on an abelian variety there is a dual polarization on the dual abelian variety. In this note we extend this notion of duality to families ofâ€¦ (More)

Let X be a smooth projective curve of genus g â‰¥ 2 over an algebraically closed field k of characteristic p > 0. Let MX be the moduli space of semistable rank-2 vector bundles over X with trivialâ€¦ (More)

Let G be a finite group, Î› an absolutely irreducible Z[G]-module and w a weight of Î›. To any Galois covering with group G we associate two correspondences, the Schur and the Kanev correspondence. Weâ€¦ (More)

An abelian variety admits only a finite number of isomorphism classes of principal polarizations. The paper gives an interpretation of this number in terms of class numbers of definite Hermitianâ€¦ (More)

The Prym variety of a pair of coverings is defined roughly speaking as the complement of the Prym variety of one morphism in the Prym variety of another morphism. We show that this definition isâ€¦ (More)

Let Ï€ : Z â†’ X be a Galois covering of smooth projective curves with Galois group the Weyl group of a simple and simply connected Lie group G. For any dominant weight Î» consider the curve Y =â€¦ (More)

The Prym map of type (g, n, r) associates to every cyclic covering of degree n of a curve of genus g, ramified at a reduced divisor of degree r, the corresponding Prym variety. We show that theâ€¦ (More)