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__NOTOC__
= Mathematics Colloquium =
= Mathematics Colloquium =


All colloquia are on Fridays at 4:00 pm in Van Vleck B239, '''unless otherwise indicated'''.
All colloquia are on Fridays at 4:00 pm in Van Vleck B239, '''unless otherwise indicated'''.


<!-- ==[[Tentative Colloquia|Tentative schedule for next semester]] == -->
== Spring 2018 ==


== Fall 2016  ==
 
{| cellpadding="8"
{| cellpadding="8"
!align="left" | date   
!align="left" | date   
Line 15: Line 11:
!align="left" | host(s)
!align="left" | host(s)
|-
|-
|September 9
|January 30
|  
| [http://www.math.columbia.edu/~chaoli/ Li Chao] (Columbia)
|[[#  |    ]]
|[[# TBA|  TBA ]]
|
| Jordan Ellenberg
|
|
|-
|-
|September 16
|February 2
|[http://www.math.cmu.edu/~ploh/ Po-Shen Loh] (CMU)
| [https://scholar.harvard.edu/tfai/home Thomas Fai] (Harvard)
|Directed paths: from Ramsey to Pseudorandomness
|[[# TBA|  TBA  ]]
|Ellenberg
| Spagnolie, Smith
|
|
|-
|-
|September 23
| March 16
| [http://www.math.wisc.edu/~craciun/ Gheorghe Craciun] (UW-Madison)
|[https://math.dartmouth.edu/~annegelb/ Anne Gelb] (Dartmouth)
|Toric Differential Inclusions and a Proof of the Global Attractor Conjecture
|[[# TBA|  TBA ]]
| Street
| WIMAW
|[[#  |    ]]
|
|-
|September 30
|[http://math.uga.edu/~magyar/ Akos Magyar]  (University of Georgia)
|Geometric Ramsey theory
| Cook
|
|
|-
|-
|October 7
|April 4 (Wednesday)
|  
| [http://math.ucr.edu/home/baez/ John Baez] (UC Riverside)
|[[# |   ]]
|[[# TBA| TBA  ]]
|
| Craciun
|
|
|-
|-
|October 14
| April 6
[https://www.math.lsu.edu/~llong/ Ling Long] (LSU)
| Reserved
|Hypergeometric functions over finite fields
|[[# TBA|  TBA ]]
| Yang
| Melanie
|
|
|-
|-
|October 21
| April 13
|'''No colloquium this week'''
| [https://www.math.brown.edu/~jpipher/ Jill Pipher] (Brown)
|[[#  |    ]]
|[[# TBA|  TBA  ]]
|
|
|-
|'''Tuesday, October 25, 9th floor'''
|[http://users.math.yale.edu/users/steinerberger/ Stefan Steinerberger] (Yale)
|Three Miracles in Analysis
|Seeger
|
|-
|October 28, 9th floor
|  [http://order.ph.utexas.edu/people/Reichl.htm Linda Reichl] (UT Austin)
|Microscopic hydrodynamic modes in a binary mixture
|Minh-Binh Tran
|
|-
|'''Monday, October 31, B239'''
[https://math.berkeley.edu/~kpmann/ Kathryn Mann] (Berkeley)
|Groups acting on the circle
|Smith
|
|-
|November 4
|
|
|
|
|-
|'''Monday, November 7 at 4:30, 9th floor''' ([http://www.ams.org/meetings/lectures/maclaurin-lectures AMS Maclaurin lecture])
| [http://www.massey.ac.nz/massey/expertise/profile.cfm?stref=339830 Gaven Martin] (New Zealand Institute for Advanced Study)
|Siegel's problem on small volume lattices
| Marshall
|
|-
|November 11
|  Reserved for possible job talks
|[[# |    ]]
|
|
|-
|'''Wednesday, November 16, 9th floor'''
|  [http://math.uchicago.edu/~klindsey/ Kathryn Lindsey] (U Chicago)
|Shapes of Julia Sets
|Michell
|
|-
|November 18, B239
|[http://www-personal.umich.edu/~asnowden/ Andrew Snowden] (University of Michigan)
|Recent progress in representation stability
|Ellenberg
|
|-
|'''Monday, November 21, 9th floor'''
|[https://www.fmi.uni-sofia.bg/fmi/logic/msoskova/index.html Mariya Soskova] (University of Wisconsin-Madison)
|Definability in degree structures
|Smith
|
|-
|November 25
|  '''Thanksgiving break'''
|[[# |    ]]
|
|
|-
|December 2, 9th floor
|  [http://math.columbia.edu/~hshen/ Hao Shen] (Columbia)
|TBA
|Roch
|
|-
|'''Monday, December 5, B239'''
|  [https://www.math.wisc.edu/~wang/ Botong Wang] (UW Madison)
|TBA
|Maxim
|
|-
|December 9
|  [http://math.uchicago.edu/~awbrown/ Aaron Brown] (Chicago)
|TBA
|Kent
|}
 
== Spring 2017  ==
 
{| cellpadding="8"
!align="left" | date 
!align="left" | speaker
!align="left" | title
!align="left" | host(s)
|-
|January 20
|Reserved for possible job talks 
|[[#  |    ]]
|
|-
|January 27
|Reserved for possible job talks
|[[# |    ]]
|
|
|-
|February 3
|
|[[#  |    ]]
|
|
|-
|February 6 (Wasow lecture)
| Benoit Perthame (University of Paris VI)
|[[# TBA|  TBA ]]
| Jin
|  
|-
|February 10 (WIMAW lecture)
| Alina Chertock (NC State Univ.)
|[[# |  ]]  
| WIMAW
| WIMAW
|
|
|-
|-
|February 17
| April 25 (Wednesday)
| [http://web.math.ucsb.edu/~ponce/ Gustavo Ponce] (UCSB)
| Hitoshi Ishii (Waseda University) Wasow lecture
|[[#   |     ]]
|[[# TBA| TBA  ]]
| Minh-Binh Tran
| Tran
|
|
|-
|-
|February 24
|date
|  
| person (institution)
|[[#  |    ]]
|[[# TBA|  TBA ]]
|  
| hosting faculty
|
|
|-
|-
|March 3
|date
| [http://www.math.utah.edu/~bromberg/ Ken Bromberg] (University of Utah)
| person (institution)
|[[# |   ]]
|[[# TBA| TBA  ]]
|Dymarz
| hosting faculty
|
|
|-
|-
|Tuesday, March 7, 4PM (Distinguished Lecture)
|date
| [http://pages.iu.edu/~temam/  Roger Temam] (Indiana University)  
| person (institution)
|[[#  |    ]]
|[[# TBA|  TBA ]]
|Smith
| hosting faculty
|
|
|-
|-
|Wednesday, March 8, 2:25PM
|date
| [http://pages.iu.edu/~temam/  Roger Temam] (Indiana University)  
| person (institution)
|[[#  |    ]]
|[[# TBA|  TBA ]]
|Smith
| hosting faculty
|
|
|-
|-
|March 10
|date
| '''No Colloquium'''
| person (institution)
|[[# |   ]]
|[[# TBA| TBA  ]]
|
| hosting faculty
|
|
|-
|-
|March 17
|date
| [https://services.math.duke.edu/~pierce/ Lillian Pierce] (Duke University)  
| person (institution)
| TBA
|[[# TBA|  TBA ]]
| M. Matchett Wood
| hosting faculty
|
|
|-
|-
|March 24
|date
| '''Spring Break'''
| person (institution)
|[[# |   ]]
|[[# TBA| TBA  ]]
|
| hosting faculty
|
|
|-
|-
|Wednesday, March 29 (Wasow)
|date
| [https://math.nyu.edu/faculty/serfaty/ Sylvia Serfaty] (NYU)  
| person (institution)
|[[# TBA|   TBA]]
|[[# TBA| TBA ]]
|Tran
| hosting faculty
|
|
|-
|-
|March 31
|date
| '''No Colloquium'''
| person (institution)
|[[# |   ]]
|[[# TBA| TBA  ]]
|
| hosting faculty
|
|-
|April 7
| [http://www.math.uiuc.edu/~schenck/ Hal Schenck]
|[[# |    ]]
|Erman
|
|
|-
|April 14
|  Wilfrid Gangbo
|[[# |    ]]
|Feldman & Tran
|
|-
|April 21
|  [http://www.math.stonybrook.edu/~mde/ Mark Andrea de Cataldo]  (Stony Brook)
|TBA
| Maxim
|
|-
|April 28
| [http://users.cms.caltech.edu/~hou/ Thomas Yizhao Hou] 
|[[# TBA|  TBA  ]]
|Li
|}
|}


== Abstracts ==
=== September 16: Po-Shen Loh (CMU) ===
Title: Directed paths: from Ramsey to Pseudorandomness


Abstract: Starting from an innocent Ramsey-theoretic question regarding directed
== Spring Abstracts ==
paths in graphs, we discover a series of rich and surprising connections
that lead into the theory around a fundamental result in Combinatorics:
Szemeredi's Regularity Lemma, which roughly states that every graph (no
matter how large) can be well-approximated by a bounded-complexity
pseudorandom object.  Using these relationships, we prove that every
coloring of the edges of the transitive N-vertex tournament using three
colors contains a directed path of length at least sqrt(N) e^{log^* N}
which entirely avoids some color.  The unusual function log^* is the
inverse function of the tower function (iterated exponentiation).


=== September 23: Gheorghe Craciun (UW-Madison) ===
<DATE>: <PERSON> (INSTITUTION)
Title: Toric Differential Inclusions and a Proof of the Global Attractor Conjecture
Title: <TITLE>


Abstract: The Global Attractor Conjecture says that a large class of polynomial dynamical systems, called toric dynamical systems, have a globally attracting point within each linear invariant space. In particular, these polynomial dynamical systems never exhibit multistability, oscillations or chaotic dynamics.
Abstract: <ABSTRACT>


The conjecture was formulated by Fritz Horn in the early 1970s, and is strongly related to Boltzmann's H-theorem.
== Past Colloquia ==
 
We discuss the history of this problem, including the connection between this conjecture and the Boltzmann equation. Then, we introduce toric differential inclusions, and describe how they can be used to prove this conjecture in full generality.
 
=== September 30: Akos Magyar (University of Georgia) ===
Title: Geometric Ramsey theory
 
Abstract: Initiated by Erdos, Graham, Montgomery and others in the 1970's, geometric Ramsey theory studies geometric configurations, determined up to translations, rotations and possibly dilations, which cannot be destroyed by finite partitions of Euclidean spaces. Later it was shown by ergodic and Fourier analytic methods that such results are also possible in the context of sets of positive upper density in Euclidean spaces or the integer lattice. We present a new approach, motivated by developments in arithmetic combinatorics, which provide new results as well new proofs of some classical results in this area.
 
=== October 14: Ling Long (LSU) ===
Title: Hypergeometric functions over finite fields
 
Abstract: Hypergeometric functions are special functions with lot of
symmetries.  In this talk, we will introduce hypergeometric functions over finite
fields, originally due to Greene, Katz and McCarthy, in a way that is
parallel to the classical hypergeometric functions, and discuss their
properties and applications to character sums and the arithmetic of
hypergeometric abelian varieties.
This is a joint work with Jenny Fuselier, Ravi Ramakrishna, Holly Swisher, and Fang-Ting Tu.
 
=== Tuesday, October 25, 9th floor: Stefan Steinerberger (Yale) ===
Title: Three Miracles in Analysis
 
Abstract: I plan to tell three stories: all deal with new points of view on very classical objects and have in common that there is a miracle somewhere. Miracles are nice but difficult to reproduce, so in all three cases the full extent of the underlying theory is not clear and many interesting open problems await. (1) An improvement of the Poincare inequality on the Torus that encodes a lot of classical Number Theory. (2) If the Hardy-Littlewood maximal function is easy to compute, then the function is sin(x). (Here, the miracle is both in the statement and in the proof). (3) Bounding classical integral operators (Hilbert/Laplace/Fourier-transforms) in L^2 -- but this time from below (this problem originally arose in medical imaging). Here, the miracle is also known as 'Slepian's miracle' (this part is joint work with Rima Alaifari, Lillian Pierce and Roy Lederman).
 
=== October 28: Linda Reichl (UT Austin) ===
Title: Microscopic hydrodynamic modes in a binary mixture
 
Abstract: Expressions for propagation speeds and decay rates of hydrodynamic modes in a binary mixture can be obtained directly from spectral properties of the Boltzmann equations describing the mixture. The derivation of hydrodynamic behavior from the spectral properties of the kinetic equation provides an alternative to Chapman-Enskog theory, and removes the need for lengthy calculations of transport coefficients in the mixture. It also provides a sensitive test of the completeness of kinetic equations describing the mixture. We apply the method to a hard-sphere binary mixture and show that it gives excellent agreement with light scattering experiments on noble gas mixtures.
 
===Monday, October 31: Kathryn Mann (Berkeley) ===
Title: Groups acting on the circle
 
Abstract:  Given a group G and a manifold M, can one describe all the actions of G on M?  This is a basic and natural question from geometric topology, but also a very difficult one -- even in the case where M is the circle, and G is a familiar, finitely generated group. 
 
In this talk, I’ll introduce you to the theory of groups acting on the circle, building on the perspectives of Ghys, Calegari, Goldman and others.  We'll see some tools, old and new, some open problems, and some connections between this theory and themes in topology (like foliated bundles) and dynamics. 
 
===November 7: Gaven Martin (New Zealand Institute for Advanced Study) ===
Title: Siegel's problem on small volume lattices
 
Abstract: We outline in very general terms the history and the proof of the identification
of the minimal covolume lattice of hyperbolic 3-space as the 3-5-3
Coxeter group extended by the involution preserving the symmetry of this
diagram. This gives us the smallest regular tessellation of hyperbolic 3-space.
This solves (in three dimensions) a problem posed by Siegel in 1945.  Siegel solved this problem in two dimensions by deriving the
signature formula identifying the (2,3,7)-triangle group as having minimal
co-area.
There are strong connections with arithmetic hyperbolic geometry in
the proof, and the result has applications in the maximal symmetry groups
of hyperbolic 3-manifolds in much the same way that Hurwitz's 84g-84 theorem
and Siegel's result do.
 
===Wednesday, November 16 (9th floor): Kathryn Lindsey (U Chicago) ===
Title: Shapes of Julia Sets
 
Abstract: The filled Julia set of a complex polynomial P is the set of points whose orbit under iteration of the map P is bounded.  William Thurston asked "What are the possible shapes of polynomial Julia sets?"  For example, is there a polynomial whose Julia set looks like a cat, or your silhouette, or spells out your name?  It turns out the answer to all of these is "yes!"  I will characterize the shapes of polynomial Julia sets and present an algorithm for constructing polynomials whose Julia sets have desired shapes.


===November 18: Andrew Snowden (University of Michigan)===
[[Colloquia/Blank|Blank Colloquia]]
Title: Recent progress in representation stability


Abstract:  Representation stability is a relatively new field that studies
[[Colloquia/Fall2017|Fall 2017]]
somewhat exotic algebraic structures and exploits their properties to
prove results (often asymptotic in nature) about objects of interest.
I will describe some of the algebraic structures that appear (and
state some important results about them), give a sampling of some
notable applications (in group theory, topology, and algebraic
geometry), and mention some open problems in the area.


===Monday, November 21:  Mariya Soskova (University of Wisconsin-Madison)===
[[Colloquia/Spring2017|Spring 2017]]
Title:  Definability in degree structures


Abstract:  Some incomputable sets are more incomputable than others. We use
[[Archived Fall 2016 Colloquia|Fall 2016]]
Turing reducibility and enumeration reducibility to measure the
relative complexity of incomputable sets. By identifying sets of the
same complexity, we can associate to each reducibility a degree
structure: the partial order of the Turing degrees and the partial
order of the enumeration degrees. The two structures are related in
nontrivial ways. The first has an isomorphic copy in the second and
this isomorphic copy is an automorphism base. In 1969, Rogers asked a
series of questions about the two degree structures with a common
theme: definability. In this talk I will introduce the main concepts
and describe the work that was motivated by these questions.
 
== Past Colloquia ==


[[Colloquia/Spring2016|Spring 2016]]
[[Colloquia/Spring2016|Spring 2016]]

Revision as of 15:53, 8 January 2018

Mathematics Colloquium

All colloquia are on Fridays at 4:00 pm in Van Vleck B239, unless otherwise indicated.

Spring 2018

date speaker title host(s)
January 30 Li Chao (Columbia) TBA Jordan Ellenberg
February 2 Thomas Fai (Harvard) TBA Spagnolie, Smith
March 16 Anne Gelb (Dartmouth) TBA WIMAW
April 4 (Wednesday) John Baez (UC Riverside) TBA Craciun
April 6 Reserved TBA Melanie
April 13 Jill Pipher (Brown) TBA WIMAW
April 25 (Wednesday) Hitoshi Ishii (Waseda University) Wasow lecture TBA Tran
date person (institution) TBA hosting faculty
date person (institution) TBA hosting faculty
date person (institution) TBA hosting faculty
date person (institution) TBA hosting faculty
date person (institution) TBA hosting faculty
date person (institution) TBA hosting faculty
date person (institution) TBA hosting faculty
date person (institution) TBA hosting faculty
date person (institution) TBA hosting faculty


Spring Abstracts

<DATE>: <PERSON> (INSTITUTION) Title: <TITLE>

Abstract: <ABSTRACT>

Past Colloquia

Blank Colloquia

Fall 2017

Spring 2017

Fall 2016

Spring 2016

Fall 2015

Spring 2015

Fall 2014

Spring 2014

Fall 2013

Spring 2013

Fall 2012