Department of

Mathematics


Seminar Calendar
for events the day of Thursday, January 23, 2020.

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Questions regarding events or the calendar should be directed to Tori Corkery.
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Thursday, January 23, 2020

11:00 am in 241 Altgeld Hall,Thursday, January 23, 2020

Heights and p-adic Hodge Theory

Lucia Mocz (University of Chicago)

Abstract: We discuss connections between p-adic Hodge theory and the Faltings height. Most namely, we show how new tools in p-adic Hodge theory can be used to prove new Northcott properties satisfied by the Faltings height, and demonstrate phenomenon which are otherwise predicted by various height conjectures. We will focus primarily on the Faltings height of CM abelian varieties where the theory can be made to be computational and explicit.

2:00 pm in 243 Altgeld Hall,Thursday, January 23, 2020

Free Banach Lattices

Vladimir Troitsky (University of Alberta)

Abstract: A free Banach lattice is the largest Banach lattice generated by a set of given cardinality. Similarly, a Banach lattice $X$ is free over a Banach space $E$ if $X$ is the largest Banach lattice which contains $E$ as a subspace and is generated by it. Equivalently, every bounded linear operator from $E$ to an arbitrary Banach lattice $Y$ extends to a lattice homomorphism from $X$ to $Y$ of the same norm. In the talk, we will discuss several methods of generating free vector and Banach lattices.

3:00 pm in 245 Altgeld Hall,Thursday, January 23, 2020

Application of Random Effects in Dependent Compound Risk Model

Himchan Jeong (University of Connecticut)

Abstract: In ratemaking for general insurance, the calculation of a pure premium has traditionally been based on modeling both frequency and severity in an aggregated claims model. Additionally for simplicity, it has been a standard practice to assume the independence of loss frequency and loss severity. However, in recent years, there has been sporadic interest in the actuarial literature exploring models that departs from this independence. Besides, usual property and casualty insurance enables us to explore the benefits of using random effects for predicting insurance claims observed longitudinally, or over a period of time. Thus, in this article, a research work is introduced with utilizes random effects in dependent two-part model for insurance ratemaking, testing the presence of random effects via Bayesian sensitivity analysis with its own theoretical development as well as empirical results and performance measures using out-of-sample validation procedures.

4:00 pm in 245 Altgeld Hall,Thursday, January 23, 2020

Semistable reduction in characteristic 0

Gaku Liu (Max Planck Institute for Mathematics in the Sciences)

Abstract: Semistable reduction is a relative generalization of the classical problem of resolution of singularities of varieties; the goal is, given a surjective morphism $f : X \to B$ of varieties in characteristic 0, to change $f$ so that it is "as nice as possible". The problem goes back to at least Kempf, Knudsen, Mumford, and Saint-Donat (1973), who proved a strongest possible version when $B$ is a curve. The key ingredient in the proof is the following combinatorial result: Given any $d$-dimensional polytope $P$ with vertices in $\mathbb{Z}^d$, there is a dilation of $P$ which can be triangulated into simplices each with vertices in $\mathbb{Z}^d$ and volume $1/d!$. In 2000, Abramovich and Karu proved, for any base $B$, that $f$ can be made into a weakly semistable morphism $f' : X' \to B'$. They conjectured further that $f'$ can be made semistable, which amounts to making $X'$ smooth. They explained why this is the best resolution of $f$ one might hope for. In this talk I will outline a proof of this conjecture. They key ingredient is a relative generalization of the above combinatorial result of KKMS. I will also discuss some other consequences in combinatorics of our constructions. This is joint work with Karim Adiprasito and Michael Temkin.