Nef and abundant divisors, semiampleness and canonical bundle formula

نویسندگان

چکیده

In this paper, we use canonical bundle formulas to prove various generalizations of an old theorem Kawamata on the semiampleness nef and abundant log divisors. particular, show that for klt pairs [Formula: see text] with effective, nef, nefness abundance implies semiampleness. This essentially extends Kawamata’s setting generalized abundance.

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Nef and big divisors on toric 3-folds with nef anti-canonical divisors

We show that a nef and big line bundle whose adjoint bundle has global sections on a nonsingular complete toric 3-fold with nef anticanonical divisor is normally generated. As a consequence, we see that any ample line bundle on a nonsingular toric Fano 3-fold is normally generated.

متن کامل

A Canonical Bundle Formula

A higher dimensional analogue of Kodaira's canonical bundle formula is obtained. As applications, we prove that the logcanonical ring of a klt pair with 3 is nitely generated, and that there exists an e ectively computable natural numberM such that jMK X j induces the Iitaka bering for every algebraic threefold X with Kodaira dimension = 1.

متن کامل

Base Point Free Theorems —saturation, B-divisors, and Canonical Bundle Formula—

We reformulate the Kawamata-Shokurov base point free theorem by using the notion of b-divisors and saturation of linear systems, which was introduced by Shokurov. Combining the refined Kawamata-Shokurov base point free theorem with Ambro’s canonical bundle formula, we quickly reprove the main theorem of Kawamata’s paper: Pluricanonical systems on minimal algebraic varieties, without using the n...

متن کامل

Three-dimensional Toric Morphisms with Anti-nef Canonical Divisors

In this paper, we classify projective toric birational morphisms from Gorenstein toric 3-folds onto the 3-dimensional affine space with relatively ample anti-canonical divisors.

متن کامل

SEMIAMPLENESS CRITERIA FOR DIVISORS ON M0,n

We develop new characteristic-independent combinatorial criteria for semiampleness of divisors on M0,n. As an application, we associate to a cyclic rational quadratic form satisfying a certain balancedness condition an infinite sequence of semiample line bundles. We also give several sufficient and effective conditions for an Sn-symmetric divisor on M0,n to be semiample or nef.

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

ژورنال

عنوان ژورنال: International Journal of Mathematics

سال: 2022

ISSN: ['1793-6519', '0129-167X']

DOI: https://doi.org/10.1142/s0129167x22500306