Finiteness of Log Minimal Models and Nef curves on $3$-folds in characteristic $p>5$

Abstract

In this article we prove a finiteness result on the number of log minimal models for $3$-folds in char $p>5$. We then use this result to prove a version of Batyrev's conjecture on the structure of nef cone of curves on $3$-folds in characteristic $p>5$. We also give a proof of the same conjecture in full generality in characteristic $0$. We further verify that the duality of movable curves and pseudo-effective divisors hold in arbitrary characteristic. We then give a criterion for the pseudo-effectiveness of the canonical divisor $K_X$ of a smooth projective variety in arbitrary characteristic in terms of the existence of a family of rational curves on $X$.

Some typos fixed and other minor changes. This is the final version. arXiv admin note: text overlap with arXiv:math/0610203, arXiv:0807.2294 by other authors

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