arXiv math/99011491999-01-01math.AG

Basepoint freeness for nef and big line bundles in positive characteristic

Seán Keel

备注：: 34 pages, published version
发表信息：: Ann. of Math. (2) 149 (1999), no. 1, 253-286

英文摘要：

A necessary and sufficient condition is given for semi-ampleness of a numerically effective (nef) and big line bundle in positive characteristic. One application is to the geometry of the universal stable curve over M_g, specifically, the semi-ampleness of the relative dualizing sheaf, in positive characteristic. An example is given which shows this and the semi-ampleness criterion fail in characteristic zero. A second application is to Mori's program for minimal models of 3-folds in positive characteristic, namely, to the existence of birational extremal contractions.

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