Splitting Criteria for Vector Bundles Induced by Restrictions to Divisors

Abstract

In this article we deduce criteria for the splitting and the triviality of vector bundles, by restricting them to partially ample divisors. This allows to study the problem of splitting on the total space of fibre bundles. The statements are illustrated with a number of examples. For products of minuscule homogeneous varieties, our results allow to test the splitting of vector bundles by restricting them to products of Schubert 2-planes.The triviality criteria obtained inhere are particularly suited to Frobenius split varieties, whose splitting is defined by a section in the anti-canonical line bundle. As an application, we prove that a vector bundle on a smooth toric variety X, whose anti-canonical bundle has stable base locus of co-dimension at least three, is trivial when its restrictions to the invariant divisors are trivial, with trivializations compatible along the various intersections.Theorem (splitting criteria). Let (X, O X (1)) be a smooth, complex projective variety, with dim X 3. Let V be a vector bundle on X, E := End(V ) the bundle of endomorphisms, L ∈ Pic(X) be q-ample, and D ∈ |dL|. The equivalenceholds in any of the following cases: