Discrete Okounkov bodies and higher-dimensional Weierstrass gap theory

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Chenzi Jin, Maryland
Fine Hall 110

Okounkov bodies are a beautiful generalization of moment polytopes from Hamiltonian dynamics on toric varieties. They were introduced in 2008 by Lazarsfeld鈥揗ustata and Kaveh鈥揔hovanskii to study volumes of big line bundles over a variety. In the toric setting, Ehrhart theory provides a precise understanding of how the moment polytope is approximated by discrete collections of lattice points associated to holomorphic sections. What can be said in the general setting?听 听

It turns out there is a natural notion of discrete Okounkov bodies on any projective variety and their study leads to many interesting results and problems. In this talk I will introduce discrete Okounkov bodies and explain how to use them to answer some open questions in algberaic/complex geometry. For instance, we prove the first asymptotic result for K-stability thresholds. In another direction, I will introduce volume quantiles that generalize the notion of volume and show how they lead to a study of "collapsing" (discrete) Okounkov bodies that leads to the first asymptotic result for global log canonical thresholds. Surprisingly, the latter can be viewed as a higher-dimensional Weierstrass gap theorem. Based on joint work with Y.A. Rubinstein and G. Tian.