Previous Conferences & Workshops

Oct
10
2014

Joint IAS/Princeton University Symplectic Geometry Seminar

Superconformal simple type and Witten's conjecture on the relation between Donaldson and Seiberg-Witten invariants
1:30pm|Fine 322, Princeton University

We shall discuss two new results concerning gauge-theoretic invariants of "standard" four-manifolds, namely closed, connected, four-dimensional, orientable, smooth manifolds with \(b^1 = 0\) and \(b^+ \geq 3\) and odd. We first describe how the SO(3...

Oct
09
2014

Joint IAS/Princeton University Number Theory Seminar

Euler systems from special cycles on unitary Shimura varieties and arithmetic applications
Dimitar Jetchev
4:30pm|Fine 214, Princeton University

We construct a new Euler system from a collection of special 1-cycles on certain Shimura 3-folds associated to \(U(2,1) \times U(1,1)\) and appearing in the context of the Gan--Gross--Prasad conjectures. We study and compare the action of the Hecke...

Oct
08
2014

Topology of Algebraic Varieties

The construction problem for Hodge numbers
Stefan Schreieder
11:15am|S-101

What are the possible Hodge numbers of a smooth complex projective variety? We construct enough varieties to show that many of the Hodge numbers can take all possible values satisfying the constraints given by Hodge theory. For example, there are...

Oct
07
2014

Topology of Algebraic Varieties

Two counterexamples arising from infinite sequences of flops
John Lesieutre
3:30pm|S-101

I will explain how infinite sequences of flops give rise to some interesting phenomena: first, an infinite set of smooth projective varieties that have equivalent derived categories but are not isomorphic; second, a pseudoeffective divisor for which...

Oct
07
2014

Topology of Algebraic Varieties

Chow rings and modified diagonals
2:00pm|S-101

Beauville and Voisin proved that decomposable cycles (intersections of divisors) on a projective K3 surface span a 1-dimensional subspace of the (infinite-dimensional) group of 0-cycles modulo rational equivalence. I will address the following...

Oct
07
2014

Topology of Algebraic Varieties

On Euler-Poincaré characteristics
Mark Andrea de Cataldo
11:00am|Physics Library, Bloomberg Hall 201

Report on R. Virk's arXiv:1406.4855v3. This is a fun, short and simple note with variations on the well-known theme by G. Laumon that the Euler characteristics with and without compact supports coincide.

Oct
07
2014

Computer Science/Discrete Mathematics Seminar II

Monotone submodular maximization over a matroid
10:30am|S-101

Monotone submodular maximization over a matroid (MSMM) is a fundamental optimization problem generalizing Maximum Coverage and MAX-SAT. Maximum Coverage is NP-hard to approximate better than \(1-1/e\), an approximation ratio obtained by the greedy...

Oct
06
2014

Members’ Seminar

Hodge theory, coniveau and algebraic cycles
2:00pm|S-101

My talk will be a broad introduction to what is the (mostly conjectural) higher dimensional generalization of Abel's theorem on divisors on Riemann surfaces, namely, the relationship between the structure of the group of algebraic cycles on a...