Partially positive line bundles

Presented by:
B Totaro [DPMMS, Cambridge]
Date:
Thursday 12th May 2011 - 10:30 to 11:30
Venue:
INI Seminar Room 1
Abstract:
Define a line bundle L on a projective variety to be q-ample, for a natural number q, if tensoring with high powers of L kills coherent sheaf cohomology above dimension q. Thus 0-ampleness is the usual notion of ampleness. Intuitively, a line bundle is q-ample if it is positive "in all but at most q directions". We prove some of the basic properties of q-ample line bundles. Related ideas have been used by Ottem to define what an "ample subvariety" of any codimension should mean.
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