Subadditivity of Kodaira dimensions for fibrations of three-folds in positive characteristics

2016/01/26 by Zhang, Lei
#Algebraic Geometry (math.AG) #FOS: Mathematics

paper · doi:10.48550/arxiv.1601.06907

Abstract

In this paper, we will prove subadditivity of Kodaira dimensions for a fibration with possibly singular geometric generic fiber, under certain nefness and relative semi-ampleness conditions. As an application, for a fibration f: X → Y of a smooth projective threefold over an algebraically closed field of characteristic p>5, under the assumption that Y is of general type and non-uniruled, we prove subadditivity of Kodaira dimensions when general fibers are smooth or when K_X/Y is relatively big over Y.

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