Previous Special Year Seminar

Mar
17
2015

Topology of Algebraic Varieties

$A^1$ curves on quasi-projective varieties
Qile Chen
2:00pm|S-101

In this talk, I will present the recent joint work with Yi Zhu on $A^1$-connectedness for quasi-projective varieties. The theory of $A^1$-connectedness for quasi-projective varieties is an analogue of rationally connectedness for projective...

Mar
04
2015

Topology of Algebraic Varieties

The jumping coefficients of non-Q-Gorenstein multiplier ideals
Patrick Graf
11:15am|S-101

De Fernex and Hacon associated a multiplier ideal sheaf to a pair $(X, \mathfrak a^c)$ consisting of a normal variety and a closed subscheme, which generalizes the usual notion where the canonical divisor $K_X$ is assumed to be Q-Cartier. I will...

Mar
03
2015

Topology of Algebraic Varieties

On some questions about minimal log discrepancies
2:00pm|S-101

The minimal log discrepancy is a measure of singularities of pairs. While akin to the log canonical threshold, it turns out to be much more difficult to study, with many questions still open. I will discuss a question about the boundedness of...

Mar
03
2015

Topology of Algebraic Varieties

A survey of motivic homotopy theory
Marc Levine
11:00am|Physics Library, Bloomberg Hall 201

We discuss developments in motivic homotopy theory over the last ten years, including structural aspects, the role of Postnikov towers, oriented theories and quadratic forms.

Feb
25
2015

Topology of Algebraic Varieties

Automorphisms of smooth canonically polarised surfaces in characteristic 2
Nikolaos Tziolas
11:15am|S-101

Let $X$ be a smooth canonically polarised surface defined over an algebraically closed field of characteristic 2. In this talk I will present some results about the geometry of $X$ in the case when the automorphism scheme $\mathrm{Aut}(X)$ of $X$ is...

Feb
24
2015

Topology of Algebraic Varieties

Projectivity of the moduli space of KSBA stable pairs and applications
Zsolt Patakfalvi
2:00pm|S-101

KSBA (Kollár-Shepherd-Barron-Alexeev) stable pairs are higher dimensional generalizations of (weighted) stable pointed curves. I will present a joint work in progress with Sándor Kovács on proving the projectivity of this moduli space, by showing...

Feb
18
2015

Topology of Algebraic Varieties

The cohomology groups of Hilbert schemes and compactified Jacobians of planar curves
11:15am|S-101

I will first discuss a relation between the cohomology groups (with rational coefficients) of the compactified Jacobian and those of the Hilbert schemes of a projective irreducible curve $C$ with planar singularities, which extends the classical...

Feb
17
2015

Topology of Algebraic Varieties

Proper base change for zero cycles
2:00pm|S-101

We study the restriction map to the closed fiber for the Chow group of zero-cycles over a complete discrete valuation ring. It turns out that, for proper families of varieties and for certain finite coefficients, the restriction map is an...

Feb
11
2015

Topology of Algebraic Varieties

Algebraic curves, tropical geometry, and moduli
11:15am|S-101

Tropical geometry gives a new approach to understanding old questions about algebraic curves and their moduli spaces, synthesizing techniques that range from Berkovich spaces to elementary combinatorics. I will discuss an outline of this method...

Feb
10
2015

Topology of Algebraic Varieties

Extending the Prym map
Samuel Grushevsky
2:00pm|S-101

The Torelli map associates to a genus g curve its Jacobian - a $g$-dimensional principally polarized abelian variety. It turns out, by the works of Mumford and Namikawa in the 1970s (resp. Alexeev and Brunyate in 2010s), that the Torelli map extends...