Title: Test ideals in mixed characteristic via the p-adic Riemann-Hilbert correspondence.Abstract: Multiplier ideals in characteristic zero and test ideals in positive characteristic are fundamental objects in the study of commutative algebra and birational geometry in equal characteristic. We introduce a mixed characteristic version of the multiplier / test ideal using the p-adic Riemann-Hilbert functor of Bhatt-Lurie. Under […]
Title: Equivariant birational geometry.Abstract: I will discuss new invariants of actions of finite groups on algebraic varieties and their applications (joint with A. Kresch, I. Cheltsov and Zh. Zhang).
Title: A moduli-theoretic approach to heights on stacks.Abstract: A theory of heights of rational points on stacks was recently introduced by Ellenberg, Satriano and Zureick-Brown as a tool to unify and generalize various results and conjectures about counting problems over global fields. In this talk I will present a moduli theoretic approach to heights on stacks over […]
Title: The Quillen-Lichtenbaum dimension of an algebraic variety and the integral Hodge conjecture.Abstract: I will explain a numerical invariant of complex varieties born out of the difference between algebraic and topological K-theory. In some cases, it is a birational invariant which is weaker than some known ones coming from unramified cohomology. However, it is also a derived […]
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Title: On the generalized Beauville decomposition.Abstract: Over 30 years ago, the work of Beauville and Deninger-Murre endowed the cohomology of an abelian scheme a (motivic) decomposition which splits the Leray filtration. This structure, now known as the Beauville decomposition, is induced by algebraic cycles obtained from the Fourier-Mukai coherent duality. In recent years, the study of Hitchin […]
Title: Isotrivial fibrations of hyper-Kähler manifolds.Abstract: A Lagrangian fibration of a projective hyper-Kähler manifold is called isotrivial if its smooth (abelian variety) fibers are all isomorphic to each other. Given an isotrivial fibration of a HK manifold f : X -> B with at least one rational section, we prove the following four descriptions of the fibration: […]
Title: Finite approximations as a tool for studying triangulated categories.Abstract: A metric on a category assigns lengths to morphisms, with the triangle inequality holding. This notion goes back to a 1974 article by Lawvere. We'll start with a quick review of some basic constructions, like forming the Cauchy completion of a category with respect to a metric.And […]
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