# Seminars & Events for 2011-2012

September 12, 2011
4:00pm - 6:00pm
##### Grothendieck's inequality and the propeller conjecture
###### Analysis Seminar
Speaker: Assaf Naor, New York University
Location:
Fine Hall 314
September 14, 2011
4:30pm - 6:30pm
##### Ultrametric subsets with large Hausdorff dimensions
###### Department Colloquium
Speaker: Assaf Naor, New York University
Location:
Fine Hall 314
September 15, 2011
2:15pm - 4:15pm
##### Domination when the stars are out
###### Discrete Mathematics Seminar

We algorithmize the recent structural characterization for claw-free graphs by Chudnovsky and Seymour. Building on this result, we show that several domination problems are fixed-parameter tractable, and even possess polynomial-sized kernels, on claw-free graphs.

Speaker: Matthias Mnich, International Computer Science Institute, Berkeley
Location:
Fine Hall 314
September 16, 2011
2:00pm - 4:00pm
##### Ambient metrics and exceptional holonomy
###### Differential Geometry & Geometric Analysis Seminar

Construction of pseudo-Riemannian metrics whose holonomy is an exceptional Lie group has been of interest in recent years.  This talk will outline a construction of an infinite-dimensional family of metrics in dimension 7 whose holonomy is contained in the split real form of the exceptional group $G_2$.  An open dense subset of the family has holonomy equal to $G_2$.  The datum for the construc

Speaker: Robin Graham, University of Washington
Location:
Fine Hall 314
September 16, 2011
3:00pm - 5:00pm
##### Improved Moser-Trudinger inequalities and Liouville equations on compact surfaces
###### Differential Geometry & Geometric Analysis Seminar

We consider a class of equations with exponential nonlinearities and possibly singular sources motivated from the study of abelian Chern Simons models or from the problem of prescribing a metric with conical singularities through conformal transformations.

Speaker: Andrea Malchiodi, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste
Location:
Fine Hall 314
September 20, 2011
12:15pm - 1:15pm
##### Cohen-Lenstra Heuristics

The class group of a number field, in colloquial terms, measures the failure of unique factorization in its ring of integers. Despite its central role in number theory, information about its structure, and even its size, mostly remain mysteries.

Speaker: Kevin Wilson,
Location:
Fine Hall 314
September 22, 2011
2:15pm - 4:15pm
##### Erdos-Ko-Rado-like theorems for rainbow matchings
###### Discrete Mathematics Seminar

Let $f(n,k,r)$ be the smallest number such that every set of more than $f(n,k,r)$ r-sets in $[n]$ contains a matching of size $k$. The Erdos-Ko-Rado theorem states that $f(n,2,r)=(n-1)(r-1)$. A natural conjecture is that if $F_1, F_2, ...F_k \subseteq {[n]}{r}$ are all of size larger than $f(n,k,r)$ then they possess a rainbow matching, that is, a choice of disjoint edges, one from each $F_i$.

Speaker: Ron Aharoni, Technion, Haifa
Location:
Fine Hall 224
September 22, 2011
4:30pm - 6:30pm
##### Transverse invariants in Heegaard Floer homology
###### Topology Seminar

Using the language of Heegaard Floer knot homology recently two invariants were defined for Legendrian knots. One in the standard contact 3-sphere defined by Ozsvath, Szabo and Thurston in the combinatorial settings of knot Floer homology, one by Lisca, Ozsvath, Stipsicz and Szabo in knot Floer homology for a general contact 3-manifold. Both of them naturally generalizes to transverse knots.

Speaker: Vera Vertesi, IAS and MIT
Location:
Fine Hall 314
September 23, 2011
3:00pm - 5:00pm
##### Hessian estimates for special Lagrangian equations with critical and supercritical phases
###### Differential Geometry & Geometric Analysis Seminar

We talk about a priori Hessian estimates for special Lagrangian equation with critical and supercritical phases in general higher dimensions. The "gradient" graphs of solutions are minimal Lagrangian submanifolds. Our unified approach leads to sharper estimates even for the previously known three dimensional or convex solution cases.

Speaker: Yu Yuan, University of Washington
Location:
Fine Hall 314
September 26, 2011
4:00pm - 6:00pm
##### Long-time strong instability and unbounded orbits for some nonlinear Schrödinger equations
###### Analysis Seminar

We establish a relation between long-time strong instability and the existence (in a certain generic sense) of unbounded orbits for dynamical systems on a Banach space. We then discuss some consequences of this relation for nonlinear Schrödinger equations.

Speaker: Zaher Hani, New York University
Location:
Fine Hall 314
September 26, 2011
4:30pm - 6:30pm
##### Understanding 3D Shapes Jointly
###### PACM/Applied Mathematics Colloquium

The use of 3D models in our economy and life is becoming more prevalent, in applications ranging from design and custom manufacturing, to prosthetics and rehabilitation, to games and entertainment.

Speaker: Leonidas Guibas, Stanford University
Location:
Fine Hall 214
September 27, 2011
12:30pm - 1:30pm
##### The Polynomial Method in Harmonic Analysis

We'll discuss incidence problems in harmonic analysis. I'll focus on recent progress which interestingly comes from algebra and topology. In particular, we'll examine Dvir's proof of the Kakeya conjecture over finite fields, Guth's endpoint estimate for the multilinear Kakeya function which used tools from algebraic topology and the joints problem.

Speaker: Kevin Hughes,
Location:
Fine Hall 314
September 27, 2011
4:30pm - 6:30pm
##### Recent advances in connecting and contrasting test ideals and multiplier ideals
###### Algebraic Geometry Seminar

This talk will focus on two distinct measures of singularities: test ideals (in positive characteristic) and multiplier ideals (characteristic zero). Though known for over a decade to be related via reduction to characteristic p > 0, recent advances have provided a uniform description of these invariants using regular alterations.

Speaker: Kevin Tucker, Princeton University
Location:
Fine Hall 322
September 28, 2011
2:00pm - 4:00pm
##### Some new results on the ground state of the strong coupling (solid)limit of the Bose-Hubbard Model; Possible applicability to solid He-4
###### Statistical Mechanics Seminar

The Mott insulator is accepted as the appropriate ground manifold for the strongly interacting Fermion Hubbard model, with solid He-3 as the simplest exemplar. It is a manifold because of the spin degrees of freedom, which order antiferromagneticallly due to atom exchange, below a critical temperature. No corresponding effect of exchange has been known for the Bose solid.

Speaker: P.W. Anderson, Princeton University
Location:
Fine Hall 224
September 28, 2011
4:30pm - 6:30pm
##### The black hole stability problem
###### Department Colloquium
Speaker: Mihalis Dafermos, University of Cambridge
Location:
Fine Hall 314
September 29, 2011
2:30pm - 4:30pm
##### The size of a hypergraph and its matching number
###### Discrete Mathematics Seminar

More than 40 years ago, Erdos asked to determine the maximum possible number of edges in a $k$-uniform hypergraph on n vertices with no matching of size $t$ (i.e., with no $t$ disjoint edges). Although this is one of the most basic problem on hypergraphs, progress on Erdos' question remained elusive.

Speaker: Benny Sudakov, UCLA
Location:
Fine Hall 224
September 29, 2011
3:00pm - 5:00pm
##### v1-periodic homotopy groups of SU(n)
###### Algebraic Topology Seminar

I will survey the various results that have been obtained during the past 22 years on the v1-periodic homotopy groups of $SU(n)$. The most recent work has been combinatorial fine tuning to make the statements more explicit. I will discuss conceptual differences between 2-primary and odd-primary groups and implications for actual homotopy groups

Speaker: Don Davis, Lehigh University
Location:
Fine Hall 214
September 30, 2011
3:00pm - 5:00pm
##### A Bernstein type theorem for entire Willmore graphs
###### Differential Geometry & Geometric Analysis Seminar

We show that every two-dimensional entire graphical solution to the Willmore equation with square integrable second fundamental form is a plane. This is joint work with Tobias Lamm.

Speaker: Jingyi Chen, University of British Columbia
Location:
Fine Hall 314
September 30, 2011
4:30pm - 6:30pm
##### On Singularities With Rational Homology Disk Smoothings
###### Symplectic Geometry Seminar
Speaker: Andras Stipsicz, Renyi Institute of Mathematics
Location:
IAS Room S-101
October 3, 2011
4:00pm - 6:00pm
##### On the uniqueness of solutions to the 3D periodic Gross-Pitaevskii hierarchy
###### Analysis Seminar

In this talk, we present a uniqueness result for solutions to the Gross-Pitaevskii hierarchy on the three-dimensional torus, under the assumption of an a priori spacetime bound.

Speaker: Vedran Sohinger, University of Pennsylvania
Location:
Fine Hall 314