All Events

from Monday
February 18, 2019 to Friday
May 31, 2019
Show events for:
Instructions for subscribing to Stony Brook Math Department Calendars

 Month     Agenda 

Monday
February 18, 2019

5:30 PM - 6:30 PM
5-127
Student Differential Geometry Seminar
Jordan Rainone, Stony Brook University
Metrics of negative scalar curvature

TBA


Wednesday
February 20, 2019

4:00 PM - 5:30 PM
Math Tower P-131
Algebraic geometry seminar
Junliang Shen, MIT
Perverse filtrations, Gopakumar-Vafa invariants, and hyper-kähler geometry

For a hyper-kähler variety equipped with a Lagrangian fibration, an increasing filtration is defined on its rational cohomology using the perverse t-structure. We will discuss the role played by this filtration in the study of the topology and geometry of hyper-kähler varieties, as well as the connection to curve counting invariants of Calabi-Yau 3-folds. In particular, we will discuss some recent progress on the P=W conjecture for Hitchin systems, and its compact analog for Lagrangian fibrations. Based on joint work with Qizheng Yin and Zili Zhang.


Wednesday
February 20, 2019

2:30 PM - 3:30 PM
Math Tower P-131
Mini Course / Dynamics Learning Seminar
Byung-Geun Oh, Hanyang University
Combinatorial Gauss-Bonnet Theorem and its applications

In this talk we will start with the concept of combinatorial curvature on planar graphs. After brief explanation for some progress related to combinatorial curvature, the main topic of this talk will come in, the "combinatorial Gauss-Bonnet theorem". Definitely it is the combinatorial counterpart to Gauss-Bonnet theorem in differential geometry. We will especially focus on the Gauss-Bonnet formula involving boundary (left) turns, since we found at least two reasonable applications of it.

The first application is related to the He-Schramm conjecture [1] about types of disk circle packing, which was later proved by Repp [2]. During the talk a statement stronger than the He-Schramm conjecture(i.e., Repp's theorem) will be presented, and one will see that the stronger version can be proved in a simpler way.

The next application is about isoperimetric constants on planar graphs. Suppose a given planar graph has faces and vertices whose degrees are at least $p$ and $q$, respectively, where $p$ and $q$ are natural numbers such that $1/p + 1/q < 1/2$.Then it is natural to guess that the isoperimetric constant of this graph is at least that of the $(p,q)$-regular graph, the $q$-regular planar graph all of whose faces have the same degree $p$. This `guess' was in fact conjectured by Lawrencenko, Plummer, and Zha [3], for which we could give an affirmative answer using the combinatorial Gauss-Bonnet theorem. A sketch of the proof will be given if time allows.

[1] Z. He and O. Schramm, Hyperbolic and parabolic packings, Discrete Comput. Geom. 14 (1995), no. 2, 123-149.

[2] A. Repp, Bounded valence excess and the parabolicity of tilings, Discrete Comput. Geom. 26 (2001), no. 3, 321-351.

[3] S. Lawrencenko, M. Plummer, and X. Zha, Isoperimetric constants of infinite plane graphs, Discrete Comput. Geom. 28 (2002), no. 3, 313-330.


Wednesday
February 20, 2019

1:00 PM - 2:00 PM
Math Tower P-131
Graduate Student Seminar
Taras Kolomatski, Stony Brook University
An Infinite Quantum Ramsey Theorem

Nik Weaver (2015) showed an intriguing non-commutative version of the classical Ramsey's theorem on graphs: Let $\mathcal{V}$ be a subspace of $M_n(\mathbb{C})$ which contains the identity matrix and is stable under the formation of Hermitian conjugates. If $n$ is sufficiently large, then there is a rank $k$ orthogonal projection such that $\dim (P\mathcal{V}P)$ is $1$ or $k^2$. These are the minimal and maximal possibilities for this dimension, and in these cases such a projection is called a quantum $k-$anticlique or quantum $k-$clique, respectively.

Weaver further showed that both the classical and quantum Ramsey's theorems are special cases of a general Ramsey theorem on \textit{quantum graphs}, which are modelled on such matrix spaces with the additional algebraic structure of being a bimodule of some matrix $*-$algebra. Investigation of such objects was initially motivated by quantum information theory, in which quantum graphs provided an analogue of the confusability graph in classical communication over a noisy channel. Weaver's work follows a long list of results successfully generalising classical results to this context, such as the definition of quantum Shannon capacity by Duan, Severini and Winter (2013).

In this talk, I will look at salient examples that demonstrate the difference between the classical and quantum contexts, sketch Weaver's results, and describe the process by which we successfully adapted Weaver's work demonstrate a quantum analogue of the classical infinite Ramsey's theorem in Kennedy, Kolomatski, Spivak (2017). Working in this infinite dimensional setting required functional analysis, and invited plenty of delightful nuance in topological considerations.


Wednesday
February 20, 2019

4:00 PM
Math Tower 5-127
Analysis Student Seminar
Jacob Mazor, Stony Brook University
First considerations in regularity theory

We finish our introduction to currents by looking at the case of codimension 1 currents: this is special as integral currents of codimension 1 were in fact introduced before the foundational paper by Federer and Fleming, by De Giorgi and Caccioppoli as sets of finite perimeter.
We then move on to discuss some first considerations in regularity theory: after an overview of the known regularity results for codimension 1 and for higher codimension, we will start developing some preliminaries, such as monotonicty formulas and its consequences.


Thursday
February 21, 2019

4:00 PM - 5:00 PM
Math Tower P-131
Colloquium
Ernie Croot, Georgia Tech
Long Progressions in Sumsets

An old question in additive number theory is determining the length of the longest progression in a sumset A+B = {a + b : a in A, b in B}, given that A and B are "large" subsets of {1,2,...,n}. I will survey some of the results on this problem, including a discussion of the methods, and also will discuss some open questions and conjectures.


Friday
February 22, 2019

10:00 AM - 11:00 AM
Math Tower 5-127
RTG Student Geometry Seminar
Lisa Marquand, Stony Brook University
The Dolbeault Groupoid

In this talk, we define the Dolbeault groupoid of rank one Higgs bundles over a compact Riemann surface. We will focus on explaining how hermitian metrics relate unitary connections to holomorphic line bundles.


Friday
February 22, 2019

4:00 PM - 6:00 PM
P-131 Math Tower
Geometric Analysis Learning Seminar
Demetre Kazaras, Stony Brook University
Bray's proof of the Penrose Conjecture


Friday
February 22, 2019

2:30 PM - 3:30 PM
Math Tower P-131
Dynamical Systems Seminar
Kasra Rafi, University of Toronto
Counting of the number of simple closed curves on a surface, revisited

TBA


Tuesday
February 26, 2019

1:00 PM - 2:30 PM
P-131
Grad / Postdoc Professional Development Seminar
Stony Brook Faculty, Stony Brook University
Applying for NSF grants

With Aliakbar Daemi, Bob Hough, Mark Mclean, and Christian Schnell. Each of us is going to talk about their experience with writing a grant proposal, applying to the NSF, getting feedback from the NSF, etc. We'll share some of the documents, and of course answer questions. We'll also be happy to give specific advice to those of you who are thinking about applying for a grant this fall.


Wednesday
February 27, 2019

4:00 PM - 5:30 PM
Math Tower P-131
Algebraic geometry seminar
Benjamin Bakker, University of Georgia
Hodge theory and o-minimality

The cohomology groups of complex algebraic varieties come equipped with a powerful invariant called a Hodge structure. Going back to foundational work of Griffiths, Hodge theory has found many important applications to algebraic and arithmetic geometry, but its intrinsically analytic nature often leads to complications. Recent joint work with Y. Brunebarbe, B. Klingler, and J. Tsimerman has shown that in fact many Hodge-theoretic constructions can be carried out in an intermediate geometric category, and o-minimality provides the crucial tameness hypothesis to make this precise. In this talk I will describe how this perspective can be used to easily recover an important theorem of Cattani--Deligne--Kaplan on the algebraicity of Hodge loci and to prove a conjecture of Griffiths on the quasiprojectivity of the images of period maps.


Thursday
February 28, 2019

4:00 PM - 5:00 PM
Math Tower P-131
Colloquium
Benjamin Bakker, University of Georgia
o-minimal GAGA

A complex algebraic variety can be naturally considered as a complex analytic space. Working with the analytic space often has many advantages, as for instance there are many more complex analytic functions than algebraic ones. For this perspective to be useful in algebraic geometry, it is necessary to also go backwards---that is, to characterize when analytic constructions starting with algebraic varieties return algebraic varieties. One powerful answer to this question is provided by Serre's celebrated GAGA theorem. It generalizes an earlier result of Chow asserting that closed complex analytic subspaces of a compact algebraic variety are in fact algebraic. Both of these theorems easily fail for non-compact algebraic varieties.

In this talk I will explain joint work with Y. Brunebarbe and J. Tsimerman which shows that Serre's GAGA theorem extends to the non-compact case if one restricts to analytic structures that are "tame" in a sense made precise by the model-theoretic notion of o-minimality. We will also explain why this result has important applications to Hodge theory.


Thursday
February 28, 2019

1:00 PM
Math Tower 5-127
Symplectic Geometry Seminar
Guillem Cazassus, Indiana
TBA

TBA


Friday
March 01, 2019

2:30 PM - 3:30 PM
Math Tower P-131
Dynamical Systems Seminar
Zoran Sunic, Hofstra University
Schreier spectra of some iterated monodromy groups

We discuss calculation of spectra of several iterated monodromy groups, such as the Hanoi Towers group $H$ and one of its subgroups, the “tangled odometers group“ $T$.

The Hanoi Towers group is the iterated monodromy group of the $3$-dimensional, post-critically finite, rational map $z→ z^2 – 16/(27z)$ and it models the well-known Hanoi Towers Problem. The subgroup $T$ is the iterated monodromy group of the post-critically finite, cubic polynomial $z→ -z^3/2 + 3z/2$ whose two critical points are fixed.

The groups act on the ternary rooted tree and on its boundary. The spectrum of the Schreier graphs of these actions were, in both cases, shown to consist of a countable set of isolated points and a Cantor set to which the isolated points accumulate via backward iterations of a quadratic polynomial. In both cases, the calculation is facilitated by first introducing a higher dimensional rational map, which is then shown to be semi-conjugate to a one-dimensional map.

Time permitting, we will also discuss the case of iterated monodromy groups of arbitrary conservative polynomials.


Tuesday
March 05, 2019

1:00 PM - 2:30 PM
P-131
Grad / Postdoc Professional Development Seminar
Graduate students, Stony Brook University
Recital practice I

Practice meeting for the graduate student recitals on March 26/27. Please attend and give some feedback to the speakers!


Wednesday
March 06, 2019

2:30 PM - 3:30 PM
Math Tower P-131
Mini Course / Dynamics Learning Seminar
Jonguk Yang, University of Michigan
TBA

TBA


Wednesday
March 06, 2019

4:00 PM - 5:30 PM
Math Tower P-131
Algebraic geometry seminar
Sophie Morel, Princeton
TBA

TBA


Thursday
March 07, 2019

2:15 PM
Math Tower 5-127
Symplectic Geometry Seminar
Nate Bottman, IAS/Princeton
TBA

TBA


Thursday
March 07, 2019

2:30 PM
P-131
Analysis Seminar
Guy David, Ball State University
Lipschitz differentiability, embeddings, and rigidity for group actions

We discuss a class of metric spaces that, despite being non-Euclidean, support a first-order calculus for Lipschitz functions developed by Cheeger. After introducing these spaces, we will survey some of their embedding properties and explain a theorem of the speaker and Kyle Kinneberg concerning embeddings in Carnot groups. Then we will explain an application of this last result to a problem on group actions in hyperbolic geometry.


Thursday
March 07, 2019

4:00 PM - 5:00 PM
Math Tower P-131
Colloquium
Stephen Miller, Rutgers University
Sphere packing, Fourier interpolation, and the Universal Optimality Theorem

I will discuss recent work on the optimal arrangement of points in euclidean space. In addition to the solution to the sphere packing problem in dimensions 8 and 24 from 2016, the "Universal Optimality" conjecture has now been proved in these dimensions as well. This shows that E8 and the Leech lattice minimize energy for any completely monotonic function of distance-squared, a fact which was previously not known for any configuration of points in any dimension > 1. Beyond giving a new proof of these sphere packing results, Universal Optimality also gives information about long-range interactions. Another application is to find the global minimum of the log-determinant of the laplacian among flat tori in those dimensions. The techniques involve arranging both a function and its Fourier transform to vanish at certain points, which leads to a new interpolation formula that recovers a radial Schwartz function from the values of it, its Fourier transform, and their derivatives, at special arithmetic points. Finally, fitting with the theme of the “Automorphic Structure” workshop, the interpolation formula reduces to an identity involving modular forms. (joint with Henry Cohn, Abhinav Kumar, Danylo Radchenko, and Maryna Viazovska)


Thursday
March 07, 2019

1:00 PM
Math Tower 5-127
Symplectic Geometry Seminar
Yuhan Sun, Stony Brook University
TBA

TBA


Friday
March 08, 2019

2:30 PM - 3:30 PM
Math Tower P-131
Dynamical Systems Seminar
Jonguk Yang, University of Michigan
TBA

TBA


Tuesday
March 12, 2019

1:00 PM - 2:30 PM
P-131
Grad / Postdoc Professional Development Seminar
Graduate students, Stony Brook University
Recital practice II

Practice meeting for the graduate student recitals on March 26/27. Please attend and give some feedback to the speakers!


Tuesday
March 12, 2019

4:00 PM - 5:00 PM
Math Tower P-131
Geometry/Topology Seminar
Fedor Manin, Ohio State University
Rational homotopy and topological isoperimetry

Soon after Sullivan introduced his model of rational homotopy theory in the 1970's, Gromov noted that the theory had some metric consequences for maps between compact manifolds or simplicial complexes. I will present a systematic view of this relationship which gives a powerful tool for, among other things, resolving the following type of question, asked by Gromov twenty years later:

Given two $L$-Lipschitz maps $f, g: X → Y$, where $X$ and $Y$ are nice compact metric spaces, what is the optimal Lipschitz constant of a homotopy between them?

I will also try to explain why this question is fundamental to quantitative topology.


Wednesday
March 13, 2019

4:00 PM - 5:30 PM
Math Tower P-131
Algebraic geometry seminar
Dan Abramovich, Brown University
Resolving singularities in families

Semistable reduction is often the first step in constructing
compactified moduli spaces, and can be used to discover their
properties. I will describe work-in-progress with Michael Temkin and
Jaroslaw Wlodarczyk in which we prove functorial semistable reduction
for families of varieties in characteristic 0, refining work with Karu
from 2000. Techniques developed for moduli spaces enter in unexpected
ways.


Thursday
March 14, 2019

1:00 PM
Math Tower 5-127
Symplectic Geometry Seminar
Weiwei Wu, University of Georgia
TBA

TBA


Thursday
March 14, 2019

2:30 PM
P-131
Analysis Seminar
Lutz Warnke, Georgia Tech
TBA

TBA


Wednesday
March 20, 2019

4:00 PM - 5:30 PM
Math Tower P-131
Algebraic geometry seminar

Spring Break!


Tuesday
March 26, 2019

4:00 PM - 5:00 PM
S-240
Special Lectures
Graduate students, Stony Brook University
Graduate student recitals 1


Wednesday
March 27, 2019

4:00 PM - 5:30 PM
S-240
Special Lectures
Graduate students, Stony Brook University
Graduate student recitals 2


Wednesday
March 27, 2019

2:30 PM - 3:30 PM
Math Tower P-131
Mini Course / Dynamics Learning Seminar
Jonathan Fraser, University of St Andrews
Dimensions of Kleinian limit sets

The dimension theory of geometrically finite Kleinian groups and their limit sets has a rich and interesting history, with the first calculation of Hausdorff dimension going back to seminal work of Patterson and Sullivan from the 1970s and 80s. There are many different (but related) notions of dimension but, nevertheless, many of the most popular coincide in this setting. In particular, the Hausdorff, box-counting, and packing dimensions of a Kleinian limit set are all given by the Poincare exponent of the group. I will discuss recent work concerning the Assouad dimension, which is not necessarily given by the Poincare exponent in the presence of parabolic points.


Wednesday
March 27, 2019

4:00 PM - 5:30 PM
Math Tower P-131
Algebraic geometry seminar

No meeting this week


Thursday
March 28, 2019

1:00 PM
Math Tower 5-127
Symplectic Geometry Seminar
Xiaomeng Xu, MIT
TBA

TBA


Thursday
March 28, 2019

4:00 PM - 5:00 PM
SCGP Auditorium
Colloquium
Simon Donaldson, SCGP
TBA


Thursday
March 28, 2019

2:30 PM
P-131
Analysis Seminar
Sean Li, University of Connecticut
TBA


Tuesday
April 02, 2019

4:00 PM - 5:30 PM
Math Tower P-131
Geometry/Topology Seminar
Simons Lectures, Stony Brook University
no Geometry/Topology seminar


Tuesday
April 02, 2019

5:30 PM - 6:30 PM
Math Tower 5-127
First and Second Year Student Seminar
Moira Chas, Stony Brook University
TBA

TBA


Wednesday
April 03, 2019

4:00 PM - 5:30 PM
Math Tower P-131
Algebraic geometry seminar
Ignacio Barros, Northeastern University
TBA


Thursday
April 04, 2019

1:00 PM
Math Tower 5-127
Symplectic Geometry Seminar
Yaron Ostrover, Tel Aviv/IAS
TBA

TBA


Thursday
April 04, 2019

2:15 PM
Math Tower 5-127
Symplectic Geometry Seminar
Barney Bramham, Bochum/IAS
TBA

TBA


Thursday
April 04, 2019

2:30 PM
P-131
Analysis Seminar
Michael Damron, Georgia Tech
TBA

TBA


Friday
April 05, 2019

2:30 PM - 3:30 PM
Math Tower P-131
Dynamical Systems Seminar
Malik Younsi, University of Hawaii
TBA

TBA


Thursday
April 11, 2019

2:30 PM
P-131
Analysis Seminar
Li-Cheng Tsai, Columbia University
TBA

TBA


Friday
April 12, 2019

2:30 PM - 3:30 PM
Math Tower P-131
Dynamical Systems Seminar
Jing Tao, University of Oklahoma
TBA

TBA


Wednesday
April 17, 2019

2:30 PM - 3:30 PM
Math Tower P-131
Mini Course / Dynamics Learning Seminar
John Milnor, Stony Brook University
TBA

TBA


Thursday
April 18, 2019

2:15 PM
Math Tower 5-127
Symplectic Geometry Seminar
Zhenkun Li, MIT
TBA

TBA


Thursday
April 18, 2019

1:00 PM
Math Tower 5-127
Symplectic Geometry Seminar
Gergő Pintér, Eotvos Lorand U.
TBA

TBA


Thursday
April 18, 2019

2:30 PM
P-131
Analysis Seminar
Antonio De Rosa, NYU
TBA

TBA


Friday
April 19, 2019

2:30 PM - 3:30 PM
Math Tower P-131
Dynamical Systems Seminar
Saeed Zakeri, CUNY
TBA

TBA


Wednesday
April 24, 2019

4:00 PM - 5:30 PM
Math Tower P-131
Algebraic geometry seminar
Valery Alexeev, University of Georgia
TBA


Thursday
April 25, 2019

1:00 PM - 2:15 PM
Math Tower 5-127
Seminar in Topology and Symplectic Geometry
Rukmini Dey, ICTS-TIFR, Bangalore
The Quillen Determinant Bundle and Geometric Quantization of Various Moduli Spaces

TBA


Thursday
April 25, 2019

4:00 PM - 5:00 PM
Math Tower P-131
Colloquium
John Morgan, SCGP
TBA


Wednesday
May 01, 2019

4:00 PM - 5:30 PM
Math Tower P-131
Algebraic geometry seminar
Andrew Obus, Baruch College CUNY
TBA

TBA


Thursday
May 02, 2019

2:30 PM
P-131
Analysis Seminar
Hoi Nguyen, Ohio State University
TBA

TBA


Show events for:
Instructions for subscribing to Stony Brook Math Department Calendars