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arXiv · 1905.12542

On a generalized canonical bundle formula for generically finite morphisms

Jingjun Han·Wenfei Liu
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Abstract

We prove a canonical bundle formula for generically finite morphisms in the setting of generalized pairs (with $\mathbb{R}$-coefficients). This complements Filipazzi's canonical bundle formula for morphisms with connected fibres. It is then applied to obtain a subadjunction formula for log canonical centers of generalized pairs. As another application, we show that the image of an anti-nef log canonical generalized pair has the structure of a numerically trivial log canonical generalized pair. This readily implies a result of Chen--Zhang. Along the way we prove that the Shokurov type convex sets for anti-nef log canonical divisors are indeed rational polyhedral sets.

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Jingjun Han, Wenfei Liu. 2020-11-18. On a generalized canonical bundle formula for generically finite morphisms. https://arxiv.org/abs/1905.12542

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