Difference between revisions of "Colloquia/Fall18"

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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 2013 ==
+
The calendar for spring 2019 can be found [[Colloquia/Spring2019|here]].
 +
 
 +
==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)
 
|-
 
|-
|Sept 6
+
|Jan 25
|[http://people.math.gatech.edu/~mbaker/ Matt Baker] (Georgia Institute of Technology)
+
| [http://www.users.miamioh.edu/randrib/ Beata Randrianantoanina] (Miami University Ohio) WIMAW
|Riemann-Roch for Graphs and Applications
+
|[[#Beata Randrianantoanina (Miami University Ohio) | Some nonlinear problems in the geometry of Banach spaces and their applications  ]]
|Ellenberg
+
| Tullia Dymarz
|-
 
|Sept 13
 
|[http://math.wisc.edu/~andrews/ Uri Andrews] (University of Wisconsin)
 
|
 
|
 
|-
 
|Sept 20
 
|[http://www.math.neu.edu/people/profile/valerio-toledano-laredo Valerio Toledano Laredo] (Northeastern)
 
 
|
 
|
|Gurevich
 
 
|-
 
|-
|'''Wed, Sept 25, 2:30PM'''
+
|Jan 30 '''Wednesday'''
|[http://mypage.iu.edu/~alindens/ Ayelet Lindenstrauss]
+
| [https://services.math.duke.edu/~pierce/ Lillian Pierce] (Duke University)
 +
|[[#Lillian Pierce (Duke University) |  Short character sums  ]]
 +
| Boston and Street
 
|
 
|
|Meyer
 
|-
 
|'''Wed, Sept 25''' (LAA lecture)
 
|[http://www.cs.berkeley.edu/~demmel/ Jim Demmel] (Berkeley)
 
|Communication Avoiding Algorithms for Linear Algebra and Beyond
 
|Gurevich
 
|-
 
|'''Thurs, Sept 26''' (LAA lecture, Joint with Applied Algebra Seminar)
 
|[http://www.cs.berkeley.edu/~demmel/ Jim Demmel] (Berkeley)
 
|Implementing Communication Avoiding Algorithms
 
|Gurevich
 
|-
 
|Sept 27 (LAA lecture)
 
|[http://www.cs.berkeley.edu/~demmel/ Jim Demmel] (Berkeley)
 
|Communication Lower Bounds and Optimal Algorithms for Programs
 
that Reference Arrays
 
|Gurevich
 
 
|-
 
|-
|Oct 4
+
|Jan 31 '''Thursday'''
|[http://www.math.tamu.edu/~sottile/ Frank Sottile] (Texas A&M)
+
| [http://www.math.tamu.edu/~dbaskin/ Dean Baskin] (Texas A&M)
 +
|[[#Dean Baskin (Texas A&M) | Radiation fields for wave equations  ]]
 +
| Street
 
|
 
|
|Caldararu
 
 
|-
 
|-
|Oct 11
+
|Feb 1
|[http://math.uchicago.edu/~wilkinso/ Amie Wilkinson] (Chicago)
+
| [https://services.math.duke.edu/~jianfeng/ Jianfeng Lu] (Duke University)
 +
|[[# TBA|  TBA  ]]
 +
| Qin
 
|
 
|
|WIMAW (Cladek)
 
|-
 
|'''Tues, Oct 15, 4PM''' (Distinguished Lecture)
 
|[http://math.mit.edu/people/profile.php?pid=1222 Alexei Borodin] (MIT)
 
|Integrable probability I
 
|Valko
 
|-
 
|'''Wed, Oct 16, 2:30PM''' (Distinguished Lecture)
 
|[http://math.mit.edu/people/profile.php?pid=1222 Alexei Borodin] (MIT)
 
|Integrable probability II
 
|Valko
 
 
|-
 
|-
|<strike>Oct 18</strike>
+
|Feb 5 '''Tuesday'''
|No colloquium due to the distinguished lecture
+
| [http://www.math.tamu.edu/~alexei.poltoratski/ Alexei Poltoratski] (Texas A&M University)
|
+
|[[# TBA|  TBA  ]]
 +
| Denisov
 
|
 
|
 
|-
 
|-
|Oct 25
+
|Feb 8
|[http://www.math.umn.edu/~garrett/ Paul Garrett] (Minnesota)
+
| [https://sites.math.northwestern.edu/~anaber/ Aaron Naber] (Northwestern)
|
+
|[[#Aaron Naber (Northwestern) |   A structure theory for spaces with lower Ricci curvature bounds  ]]
|Gurevich
+
| Street
|
 
 
|
 
|
 
|-
 
|-
|Nov 1
+
|Feb 15
|[http://www.cs.utexas.edu/~alewko/ Allison Lewko] (Microsoft Research New England)
+
|  
 +
|[[# TBA|  TBA  ]]
 +
|
 
|
 
|
|Stovall
 
 
|-
 
|-
|Nov 8
+
|Feb 22
|[http://www.math.cornell.edu/~riley/ Tim Riley] (Cornell)
+
| [https://people.math.osu.edu/cueto.5/ Angelica Cueto] (Ohio State)
 +
|[[# TBA|  TBA  ]]
 +
| Erman and Corey
 
|
 
|
|Dymarz
 
 
|-
 
|-
|Nov 15 and later
+
|March 4
|Reserved
+
| [http://www-users.math.umn.edu/~sverak/ Vladimir Sverak] (Minnesota) Wasow lecture
 +
|[[# TBA| TBA ]]
 +
| Kim
 
|
 
|
|Street
 
|}
 
 
== Spring 2014 ==
 
 
{| cellpadding="8"
 
!align="left" | date
 
!align="left" | speaker
 
!align="left" | title
 
!align="left" | host(s)
 
 
|-
 
|-
|Jan 24
+
|March 8
|
+
| [https://orion.math.iastate.edu/jmccullo/index.html Jason McCullough] (Iowa State)
|
+
|[[# TBA|  TBA  ]]
 +
| Erman
 
|
 
|
 
|-
 
|-
|Jan 31
+
|March 15
|[http://csi.usc.edu/~ubli/ubli.html Urbashi Mitra] (USC)
+
| Maksym Radziwill (Caltech)
 +
|[[# TBA|  TBA  ]]
 +
| Marshall
 
|
 
|
|Gurevich
 
 
|-
 
|-
|Feb 7
+
|March 29
|David Treumann (Boston College)
+
| Jennifer Park (OSU)
 +
|[[# TBA|  TBA  ]]
 +
| Marshall
 
|
 
|
|Street
 
 
|-
 
|-
|Feb 14
+
|April 5
|
+
| Ju-Lee Kim (MIT)
|
+
|[[# TBA|  TBA  ]]
 +
| Gurevich
 
|
 
|
 
|-
 
|-
|Feb 21
+
|April 12
|
+
| Evitar Procaccia (TAMU)
|
+
|[[# TBA|  TBA  ]]
 +
| Gurevich
 
|
 
|
 
|-
 
|-
|Feb 28
+
|April 19
|
+
| [http://www.math.rice.edu/~jkn3/ Jo Nelson] (Rice University)
|
+
|[[# TBA|  TBA  ]]
 +
| Jean-Luc
 
|
 
|
 
|-
 
|-
|March 7
+
|April 26
|
+
| [https://www.brown.edu/academics/applied-mathematics/faculty/kavita-ramanan/home Kavita Ramanan] (Brown University)
|
+
|[[# TBA|  TBA  ]]
 +
| WIMAW
 
|
 
|
 
|-
 
|-
|March 14
+
|May 3
 +
| Tomasz Przebinda (Oklahoma)
 +
|[[# TBA|  TBA  ]]
 +
| Gurevich
 
|
 
|
|
 
|
 
|-
 
|<strike>March 21</strike>
 
|'''Spring Break'''
 
|No Colloquium
 
|
 
|-
 
|March 28
 
|[http://people.math.gatech.edu/~lacey/ Michael Lacey] (GA Tech)
 
|The Two Weight Inequality for the Hilbert Transform
 
|Street
 
|-
 
|April 4
 
|[https://sites.google.com/site/katejuschenko/ Kate Jushchenko] (Northwestern)
 
|
 
|Dymarz
 
|-
 
|April 11
 
|[http://www.cs.uchicago.edu/people/risi Risi Kondor] (Chicago)
 
|
 
|Gurevich
 
|-
 
|April 18 (Wasow Lecture)
 
|[http://mathnt.mat.jhu.edu/sogge/ Christopher Sogge] (Johns Hopkins)
 
|
 
|A. Seeger
 
|-
 
|April 25
 
|[http://www.charlesdoran.net Charles Doran](University of Alberta)
 
|
 
|Song
 
|-
 
|May 2
 
|[http://www.stat.uchicago.edu/~lekheng/ Lek-Heng Lim] (Chicago)
 
|
 
|Boston
 
|-
 
|May 9
 
|[http://www.ma.utexas.edu/users/rward/ Rachel Ward] (UT Austin)
 
|
 
|WIMAW
 
 
|}
 
|}
  
 
== Abstracts ==
 
== Abstracts ==
  
===Sep 6: Matt Baker (GA Tech) ===
+
===Beata Randrianantoanina (Miami University Ohio)===
''Riemann-Roch for Graphs and Applications''
+
 
 +
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 ==
 +
 
 +
[[Colloquia/Blank|Blank]]
 +
 
 +
[[Colloquia/Fall2018|Fall 2018]]
 +
 
 +
[[Colloquia/Spring2018|Spring 2018]]
  
We will begin by formulating the Riemann-Roch theorem for graphs due to the speaker and Norine. We will then describe some refinements and applications. Refinements include a Riemann-Roch theorem for tropical curves, proved by Gathmann-Kerber and Mikhalkin-Zharkov, and a Riemann-Roch theorem for metrized complexes of curves, proved by Amini and the speaker. Applications include a new proof of the Brill-Noether theorem in algebraic geometry (work of by Cools-Draisma-Payne-Robeva), a "volume-theoretic proof" of Kirchhoff's Matrix-Tree Theorem (work of An, Kuperberg, Shokrieh, and the speaker), and a new Chabauty-Coleman style bound for the number of rational points on an algebraic curve over the rationals (work of Katz and Zureick-Brown).
+
[[Colloquia/Fall2017|Fall 2017]]
  
===Sep 25: Jim Demmel (Berkeley) ===
+
[[Colloquia/Spring2017|Spring 2017]]
''Communication Avoiding Algorithms for Linear Algebra and Beyond''
 
  
Algorithm have two costs: arithmetic and communication, i.e. moving data between levels of a memory hierarchy or processors over a network. Communication costs (measured in time or energy per operation) already greatly exceed arithmetic costs, and the gap is growing over time following technological trends. Thus our goal is to design algorithms that minimize communication. We present algorithms that attain provable lower bounds on communication, and show large speedups compared to their conventional counterparts. These algorithms are for direct and iterative linear algebra, for dense and sparse matrices, as well as direct n-body simulations. Several of these algorithms exhibit perfect strong scaling, in both time and energy: run time (resp. energy) for a fixed problem size drops proportionally to the number of processors p (resp. is independent of p). Finally, we describe extensions to algorithms involving arbitrary loop nests and array accesses, assuming only that array subscripts are affine functions of the loop indices.
+
[[Archived Fall 2016 Colloquia|Fall 2016]]
  
===Sep 26: Jim Demmel (Berkeley) ===
+
[[Colloquia/Spring2016|Spring 2016]]
''Implementing Communication Avoiding Algorithms''
 
  
Designing algorithms that avoiding communication, attaining
+
[[Colloquia/Fall2015|Fall 2015]]
lower bounds if possible, is critical for algorithms to minimize runtime and
 
energy on current and future architectures. These new algorithms can have
 
new numerical stability properties, new ways to encode answers, and new data
 
structures, not just depend on loop transformations (we need those too!).
 
We will illustrate with a variety of examples including direct linear algebra
 
(eg new ways to perform pivoting, new deterministic and randomized
 
eigenvalue algorithms), iterative linear algebra (eg new ways to reorganize
 
Krylov subspace methods) and direct n-body algorithms, on architectures
 
ranging from multicore to distributed memory to heterogeneous.
 
The theory describing communication avoiding algorithms can give us a large
 
design space of possible implementations, so we use autotuning to find
 
the fastest one automatically. Finally, on parallel architectures one can
 
frequently not expect to get bitwise identical results from multiple runs,
 
because of dynamic scheduling and floating point nonassociativity;
 
this can be a problem for reasons from debugging to correctness.
 
We discuss some techniques to get reproducible results at modest cost.
 
  
 +
[[Colloquia/Spring2014|Spring 2015]]
  
 +
[[Colloquia/Fall2014|Fall 2014]]
  
===March 28: Michael Lacey (GA Tech) ===
+
[[Colloquia/Spring2014|Spring 2014]]
''The Two Weight Inequality for the Hilbert Transform ''
 
  
The individual two weight inequality for the Hilbert transform
+
[[Colloquia/Fall2013|Fall 2013]]
asks for a real variable characterization of those pairs of weights
 
(u,v) for which the Hilbert transform H maps L^2(u) to L^2(v).
 
This question arises naturally in different settings, most famously
 
in work of Sarason. Answering in the positive a deep
 
conjecture of Nazarov-Treil-Volberg, the mapping property
 
of the Hilbert transform is characterized by a triple of conditions,
 
the first being a two-weight Poisson A2 on the pair of weights,
 
with a pair of so-called testing inequalities, uniform over all
 
intervals.  This is the first result of this type for a singular
 
integral operator.  (Joint work with Sawyer, C.-Y. Shen and Uriate-Tuero)
 
  
== Past talks ==
+
[[Colloquia 2012-2013|Spring 2013]]
  
Last year's schedule: [[Colloquia 2012-2013]]
+
[[Colloquia 2012-2013#Fall 2012|Fall 2012]]

Latest revision as of 09:43, 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