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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'''.


== Fall 2015  ==
The calendar for spring 2019 can be found [[Colloquia/Spring2019|here]].
 
Go to next semester, [[Colloquia/Spring 2016|Spring 2016]].


==Spring 2019==


{| cellpadding="8"
{| cellpadding="8"
!align="left" | date
!align="left" | date  
!align="left" | speaker
!align="left" | speaker
!align="left" | title
!align="left" | title
!align="left" | host(s)
!align="left" | host(s)
|-
| '''September 4'''
| [http://homepages.math.uic.edu/~isaac/  Isaac Goldbring] (UIC)   
| [[Colloquia#September 4:  Isaac Goldbring (UIC) | On Kirchberg's embedding problem]]
| Andrews/Lempp
|-
|-
| '''September 11'''
|Jan 25
| [https://sites.google.com/site/doronpuder/  Doron Puder] (IAS)
| [http://www.users.miamioh.edu/randrib/ Beata Randrianantoanina] (Miami University Ohio) WIMAW
| [[Colloquia#September 11:  Doron Puder (IAS) | Word-Measures on Groups]]
|[[#Beata Randrianantoanina (Miami University Ohio) | Some nonlinear problems in the geometry of Banach spaces and their applications  ]]
| Gurevich
| Tullia Dymarz
|
|-
|-
| '''September 18'''  
|Jan 30 '''Wednesday'''
| [http://homepages.math.uic.edu/~coskun/ Izzet Coskun] (UIC)
| [https://services.math.duke.edu/~pierce/ Lillian Pierce] (Duke University)
| [[Colloquia#September 18:  Izzet Coskun (UIC) | The geometry of points in the plane]]  
|[[#Lillian Pierce (Duke University) | Short character sums  ]]
| Erman
| Boston and Street
|
|-
|-
| '''September 25'''  
|Jan 31 '''Thursday'''
| [https://pantherfile.uwm.edu/ourmazd/www/ Abbas Ourmazd] (UW-Milwaukee)  
| [http://www.math.tamu.edu/~dbaskin/ Dean Baskin] (Texas A&M)
| <!-- [[Colloquia#September 25:  Abbas Ourmazd (UW-Milwaukee) | TBA]] -->
|[[#Dean Baskin (Texas A&M) | Radiation fields for wave equations  ]]
| Mitchell
| Street
|
|-
|-
| '''October 2'''
|Feb 1
|  
| [https://services.math.duke.edu/~jianfeng/ Jianfeng Lu] (Duke University)
|  
|[[# TBA|  TBA  ]]
|  
| Qin
|
|-
|-
| '''October 9'''  
|Feb 5 '''Tuesday'''
| [https://www.engr.ucsb.edu/~mgroup Igor Mezic] (UC Santa Barbara)  
| [http://www.math.tamu.edu/~alexei.poltoratski/ Alexei Poltoratski] (Texas A&M University)
| <!-- [[Colloquia#October 9: Igor Mezic (UC Santa Barbara) | TBA]] -->
|[[# TBA| TBA ]]
| Budisic, Thiffeault
| Denisov
|
|-
|-
| '''October 16'''
|Feb 8
| [http://mysite.science.uottawa.ca/hsalmasi/ Hadi Salmasian] (Ottawa)  
| [https://sites.math.northwestern.edu/~anaber/ Aaron Naber] (Northwestern)
| <!-- [[Colloquia#October 23:  Speaker (University) | title]] -->
|[[#Aaron Naber (Northwestern) |   A structure theory for spaces with lower Ricci curvature bounds  ]]
| Gurevich
| Street
|
|-
|-
| '''October 23'''
|Feb 15
| Wisconsin Science Festival.  <!-- [webpage Speaker Name] (University) -->   
|  
| <!-- [[Colloquia#October16: Speaker (University) | title]] -->
|[[# TBA|  TBA ]]
| <!-- host -->
|  
|
|-
|-
| '''October 30'''
|Feb 22
|   [http://people.brandeis.edu/~charney/Charney15.html Ruth Charney] (Brandeis)    
| [https://people.math.osu.edu/cueto.5/ Angelica Cueto] (Ohio State)
| <!-- [[Colloquia#October 30: Ruth Charney (Brandeis) | title]] -->
|[[# TBA|  TBA ]]
| Dymarz
| Erman and Corey
|
|-
|-
| '''November 6'''
|March 4
| Reserved *S <!-- Remove if no job talks -->
| [http://www-users.math.umn.edu/~sverak/ Vladimir Sverak] (Minnesota) Wasow lecture
|[[# TBA| TBA ]]
| Kim
|
|
|-
|March 8
| [https://orion.math.iastate.edu/jmccullo/index.html Jason McCullough] (Iowa State)
|[[# TBA|  TBA  ]]
| Erman
|
|
|-
|-
| '''November 13'''
|March 15
| Reserved *T <!-- Remove if no job talks -->
| Maksym Radziwill (Caltech)
|[[# TBA|  TBA ]]
| Marshall
|
|
|-
|March 29
| Jennifer Park (OSU)
|[[# TBA|  TBA  ]]
| Marshall
|
|
|-
|-
| '''November 20'''
|April 5
|  Reserved <!-- Remove if no job talks -->
| Ju-Lee Kim (MIT)
|[[# TBA|  TBA ]]
| Gurevich
|
|
|-
|April 12
|  Evitar Procaccia (TAMU)
|[[# TBA|  TBA  ]]
| Gurevich
|
|
|-
|-
| '''November 27'''
|April 19
| University Holiday
| [http://www.math.rice.edu/~jkn3/ Jo Nelson] (Rice University)
|  No Colloquium
|[[# TBA|  TBA  ]]
| Jean-Luc
|
|
|-
|-
| '''December 4'''
|April 26
|  Reserved <!-- Remove if no job talks -->
| [https://www.brown.edu/academics/applied-mathematics/faculty/kavita-ramanan/home Kavita Ramanan] (Brown University)
|
|[[# TBA|  TBA ]]
| WIMAW
|
|
|-
|-
| '''December 11'''
|May 3
|  Reserved <!-- Remove if no job talks -->
| Tomasz Przebinda (Oklahoma)
|
|[[# TBA|  TBA ]]
| Gurevich
|
|
|}
|}
Line 94: Line 118:
== Abstracts ==
== Abstracts ==


===September 4: Isaac Goldbring (UIC) ===
===Beata Randrianantoanina (Miami University Ohio)===
Title: Hindman's theorem and idempotent types


Abstract: For a set A of natural numbers, let FS(A) denote the set of sums of finitely many distinct elements of A. A set B of natural numbers is said to be an IP set if B contains FS(A) for some infinite set A. A central result in combinatorial number theory is Hindman's theorem, which states that if one finitely colors an IP set, then at least one of the colors is an IP set. The slickest proof of this result uses idempotent ultrafilters. Di Nasso suggested a model-theoretic generalization of idempotent ultrafilters, aptly named idempotent types, and asked in what completions of PA idempotent types exist. In this talk, I will show that Hindman's theorem is actually equivalent to the existence of idempotent types in all countable complete extensions of PA. This is joint work with Uri Andrews.
Title: Some nonlinear problems in the geometry of Banach spaces and their applications.


====  ====
Abstract: Nonlinear problems in the geometry of Banach spaces have been studied since the inception of the field. In this talk I will outline some of the history, some of modern applications, and some open directions of research. The talk will be accessible to graduate students of any field of mathematics.


===September 11: Doron Puder (IAS) ===
===Lillian Pierce (Duke University)===
Title: Word-Measures on Groups.


Abstract: Let w be a word in the free group on k generators, and let G be a finite (compact) group. The word w induces a measure on G by substituting the letters of w with k independent uniformly (Haar) chosen random elements of G and evaluating the product. Questions about word-measures on groups attracted attention in recent years both for their own sake and as a tool to analyze random walks on groups.
Title: Short character sums


We will explain some properties of word-measure, give examples and state conjectures. We will also talk about recent results regarding word-measures on symmetric groups and word-measures on unitary groups.
Abstract: A surprisingly diverse array of problems in analytic number theory have at their heart a problem of bounding (from above) an exponential sum, or its multiplicative cousin, a so-called character sum. For example, both understanding the Riemann zeta function or Dirichlet L-functions inside the critical strip, and also counting solutions to Diophantine equations via the circle method or power sieve methods, involve bounding such sums. In general, the sums of interest fall into one of two main regimes: complete sums or incomplete sums, with this latter regime including in particular “short sums.” Short sums are particularly useful, and particularly resistant to almost all known methods. In this talk, we will see what makes a sum “short,” sketch why it would be incredibly powerful to understand short sums, and discuss a curious proof from the 1950’s which is still the best way we know to bound short sums. We will end by describing new work which extends the ideas of this curious proof to bound short sums in much more general situations.
====  ====


===September 18: Izzet Coskun (UIC) ===
===Dean Baskin (Texas A&M)===
Title:  The geometry of points in the plane


Abstract: Grothendieck's Hilbert scheme of points is a smooth  compactification of the configuration space of points in the plane. It has close connections with combinatorics, representation theory, mathematical physics and algebraic geometry. In this talk, I will survey some of the basic properties of this beautiful space. If time permits, I will discuss joint work with Arcara, Bertram and Huizenga on codimension one subvarieties of the Hilbert scheme.
Title: Radiation fields for wave equations
====  ====


===October 9: Igor Mezic (UC Santa Barbara) ===
Abstract: Radiation fields are rescaled limits of solutions of wave equations near "null infinity" and capture the radiation pattern seen by a distant observer. They are intimately connected with the Fourier and Radon transforms and with scattering theory. In this talk, I will define and discuss radiation fields in a few contexts, with an emphasis on spacetimes that look flat near infinity. The main result is a connection between the asymptotic behavior of the radiation field and a family of quantum objects on an associated asymptotically hyperbolic space.
 
===Aaron Naber (Northwestern)===
 
Title:  A structure theory for spaces with lower Ricci curvature bounds.
 
Abstract:  One should view manifolds (M^n,g) with lower Ricci curvature bounds as being those manifolds with a well behaved analysis, a point which can be rigorously stated.  It thus becomes a natural question, how well behaved or badly behaved can such spaces be?  This is a nonlinear analogue to asking how degenerate can a subharmonic or plurisubharmonic function look like.  In this talk we give an essentially sharp answer to this question.  The talk will require little background, and our time will be spent on understanding the basic statements and examples.  The work discussed is joint with Cheeger, Jiang and with Li.


====  ====


== Past Colloquia ==
== Past Colloquia ==
[[Colloquia/Blank|Blank]]
[[Colloquia/Fall2018|Fall 2018]]
[[Colloquia/Spring2018|Spring 2018]]
[[Colloquia/Fall2017|Fall 2017]]
[[Colloquia/Spring2017|Spring 2017]]
[[Archived Fall 2016 Colloquia|Fall 2016]]
[[Colloquia/Spring2016|Spring 2016]]
[[Colloquia/Fall2015|Fall 2015]]


[[Colloquia/Spring2014|Spring 2015]]
[[Colloquia/Spring2014|Spring 2015]]

Latest revision as of 14:43, 24 January 2019

Mathematics Colloquium

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

The calendar for spring 2019 can be found here.

Spring 2019

date speaker title host(s)
Jan 25 Beata Randrianantoanina (Miami University Ohio) WIMAW Some nonlinear problems in the geometry of Banach spaces and their applications Tullia Dymarz
Jan 30 Wednesday Lillian Pierce (Duke University) Short character sums Boston and Street
Jan 31 Thursday Dean Baskin (Texas A&M) Radiation fields for wave equations Street
Feb 1 Jianfeng Lu (Duke University) TBA Qin
Feb 5 Tuesday Alexei Poltoratski (Texas A&M University) TBA Denisov
Feb 8 Aaron Naber (Northwestern) A structure theory for spaces with lower Ricci curvature bounds Street
Feb 15 TBA
Feb 22 Angelica Cueto (Ohio State) TBA Erman and Corey
March 4 Vladimir Sverak (Minnesota) Wasow lecture TBA Kim
March 8 Jason McCullough (Iowa State) TBA Erman
March 15 Maksym Radziwill (Caltech) TBA Marshall
March 29 Jennifer Park (OSU) TBA Marshall
April 5 Ju-Lee Kim (MIT) TBA Gurevich
April 12 Evitar Procaccia (TAMU) TBA Gurevich
April 19 Jo Nelson (Rice University) TBA Jean-Luc
April 26 Kavita Ramanan (Brown University) TBA WIMAW
May 3 Tomasz Przebinda (Oklahoma) TBA Gurevich

Abstracts

Beata Randrianantoanina (Miami University Ohio)

Title: Some nonlinear problems in the geometry of Banach spaces and their applications.

Abstract: Nonlinear problems in the geometry of Banach spaces have been studied since the inception of the field. In this talk I will outline some of the history, some of modern applications, and some open directions of research. The talk will be accessible to graduate students of any field of mathematics.

Lillian Pierce (Duke University)

Title: Short character sums

Abstract: A surprisingly diverse array of problems in analytic number theory have at their heart a problem of bounding (from above) an exponential sum, or its multiplicative cousin, a so-called character sum. For example, both understanding the Riemann zeta function or Dirichlet L-functions inside the critical strip, and also counting solutions to Diophantine equations via the circle method or power sieve methods, involve bounding such sums. In general, the sums of interest fall into one of two main regimes: complete sums or incomplete sums, with this latter regime including in particular “short sums.” Short sums are particularly useful, and particularly resistant to almost all known methods. In this talk, we will see what makes a sum “short,” sketch why it would be incredibly powerful to understand short sums, and discuss a curious proof from the 1950’s which is still the best way we know to bound short sums. We will end by describing new work which extends the ideas of this curious proof to bound short sums in much more general situations.

Dean Baskin (Texas A&M)

Title: Radiation fields for wave equations

Abstract: Radiation fields are rescaled limits of solutions of wave equations near "null infinity" and capture the radiation pattern seen by a distant observer. They are intimately connected with the Fourier and Radon transforms and with scattering theory. In this talk, I will define and discuss radiation fields in a few contexts, with an emphasis on spacetimes that look flat near infinity. The main result is a connection between the asymptotic behavior of the radiation field and a family of quantum objects on an associated asymptotically hyperbolic space.

Aaron Naber (Northwestern)

Title: A structure theory for spaces with lower Ricci curvature bounds.

Abstract: One should view manifolds (M^n,g) with lower Ricci curvature bounds as being those manifolds with a well behaved analysis, a point which can be rigorously stated. It thus becomes a natural question, how well behaved or badly behaved can such spaces be? This is a nonlinear analogue to asking how degenerate can a subharmonic or plurisubharmonic function look like. In this talk we give an essentially sharp answer to this question. The talk will require little background, and our time will be spent on understanding the basic statements and examples. The work discussed is joint with Cheeger, Jiang and with Li.


Past Colloquia

Blank

Fall 2018

Spring 2018

Fall 2017

Spring 2017

Fall 2016

Spring 2016

Fall 2015

Spring 2015

Fall 2014

Spring 2014

Fall 2013

Spring 2013

Fall 2012

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