## Past Seminars by Series

Fri Dec 13 |
## Special Events and Seminars1:25pm - Vincent Hall 213"p-Adic Cohomology, Exponential Sums, and Hypergeometric Functions TBATBA |

Fri Dec 06 |
## Special Events and Seminars1:25pm - Vincent Hall 213"p-Adic Cohomology, Exponential Sums, and Hypergeometric Functions TBATBA |

Fri Nov 29 |
## Special Events and Seminars1:25pm - Vincent Hall 213"p-Adic Cohomology, Exponential Sums, and Hypergeometric Functions TBATBA |

Fri Nov 22 |
## Special Events and Seminars3:30pm - Vincent Hall 20Mass Scale Image Analysis For Automated Plant Phenotyping and Classification via Machine Learning Riley O'Neill, University of St. Thomas The capacity to quantify crop architecture and morphology is foundational to the development of higher yielding cultivars via hybridization and genetic engineering. However, at the mass scale required by the science, manual plant phenotyping with physical instruments is arduous, time consuming, subjective, and a leading cause of undergraduate burnout in the UMN plant genetics department. While the process has been slightly improved with manual image analysis, such is almost as time consuming and remains subject to human error. Thereby, in efforts to further expedite phenotyping processes, circumvent human error, and provide more detailed analyses, we aim to completely automate plant phenotyping processes for the UMN plant genetics department and beyond. Working from over 15,000 soybean plants, weve advanced robust image processing platforms for measuring petiole and stem length, leaf area, leaf shape via signature curves, and branch angles via energy minimization in 2D, and begun preliminary work at 3D reconstructions from 2D data for 3D branch angles and further analyses. After data extraction and verification, we plan to implement clustering algorithms and machine learning to automatically group plant phenotypes as well as conduct principal component analysis to assemble an allometry space and identify the primary genes of influence. |

Fri Nov 22 |
## Special Events and Seminars1:25pm - Vincent Hall 213"p-Adic Cohomology, Exponential Sums, and Hypergeometric Functions TBATBA |

Fri Nov 15 |
## Special Events and Seminars1:25pm - Vincent Hall 213"p-Adic Cohomology, Exponential Sums, and Hypergeometric Functions TBATBA |

Fri Nov 08 |
## Special Events and Seminars1:25pm - Vincent Hall 213"p-Adic Cohomology, Exponential Sums, and Hypergeometric Functions Steven SperberSteven Sperber |

Fri Nov 01 |
## Special Events and Seminars1:25pm - Vincent Hall 213p-Adic Banach Spaces and Completely Continuous Endomorphisms Steven SperberSteven Sperber |

Fri Oct 25 |
## Special Events and Seminars1:25pm - Vincent Hall 213"p-Adic Cohomology, Exponential Sums, and Hypergeometric Functions TBATBA |

Fri Oct 18 |
## Special Events and Seminars1:25pm - Vincent Hall 213Trace Formula, continued Steven Sperber, University of Minnesota |

Fri Oct 11 |
## Special Events and Seminars1:25pm - Vincent Hall 213Trace Formula (continued) Steven Sperber, University of Minnesota |

Fri Oct 04 |
## Special Events and Seminars1:25pm - Vincent Hall 213"Trace Formula, I" Steven Sperber, University of Minnesota |

Fri Sep 27 |
## Special Events and Seminars1:25pm - Vincent Hall 213A p-adic analytic interpolation of a finite field character, II Steven Sperber, University of Minnesota |

Fri Sep 20 |
## Special Events and Seminars1:25pm - Vincent Hall 213A p-adic analytic interpolation of a finite field character Steven Sperber, University of Minnesota |

Fri Sep 13 |
## Special Events and Seminars1:25pm - Vincent Hall 213"p-Adic Cohomology, Exponential Sums, and Hypergeometric Functions TBATBA |

Mon Jun 10 |
## Special Events and Seminars1:30pm - Vincent Hall 364Basic Operations on Representations Andy HardtAndy Hardt We continue our crash course in finite group representation theory by looking at some important operations on representations. We start by defining the group algebra of a finite group; group representations naturally biject with modules over the group algebra. After that, we'll talk through a variety of ways to construct new representations from old, such as restriction, induction, inflation, tensor product, and we may even squeeze in symmetric and exterior powers. |

Wed Jun 05 |
## Special Events and Seminars2:00pm - Vincent Hall 570AWM Talk Mimi BoutinMimi Boutin |

Wed May 29 |
## Special Events and Seminars1:30pm - Vincent Hall 206Informal Fluids Seminar Raj BeekieRaj Beekie |

Tue May 14 |
## Special Events and Seminars3:30pm - Vincent Hall 570Singularity formation for some solutions of the incompressible Euler equation Tarek ElgindiTarek Elgindi We describe a recent construction of self-similar blow-up solutions of the incompressible Euler equation. A consequence of the construction is that there exist finite-energy $C^{1,a}$ solutions to the Euler equation which develop a singularity in finite time for some range of $a>0$. The approach we follow is to isolate a simple non-linear equation which encodes the leading order dynamics of solutions to the Euler equation in some regimes and then prove that the simple equation has stable self-similar blow-up solutions. |

Tue Apr 23 |
## Special Events and Seminars3:30pm - Vincent Hall 364Vortex filaments in the 3D Navier-Stokes equations Jacob Bedrossian, Maryland We consider solutions of the Navier-Stokes equations in 3d with vortex filament initial data of arbitrary circulation, that is, initial vorticity given by a divergence-free vector-valued measure of arbitrary strength supported on a smooth curve. First, we prove global well-posedness for perturbations of the Oseen vortex column in scaling-critical spaces. Second, we prove local well-posedness (in a sense to be made precise) when the filament is a smooth, closed, non-self-intersecting curve. Besides their physical interest as a model for the coherent vortex filament structures observed in 3d fluids, these results are the first to give well-posedness (in a certain sense) in a neighborhood of large self-similar solutions of 3d Navier-Stokes, as well as solutions which are locally approximately self-similar. Joint work with Pierre Germain and Benjamin Harrop-Griffiths. |

Thu Apr 11 |
## Special Events and Seminars2:30pm - Vincent Hall 570Informal Fluids Seminar with the speaker Samuel Punshon-Smith Samuel Punshon-SmithSamuel Punshon-Smith |

Wed Apr 10 |
## Special Events and Seminars2:30pm - Vincent Hall 213Arithmetic level raising for unitary groups and Beilinson-Bloch-Kato conjecture (II) Yifeng Liu, Yale University In this series of two talks, we will introduce the recent progress on Beilinson-Bloch-Kato conjecture for Rankin-Selberg motives of arbitrary rank. We will discuss an important technique used in the proof, namely, the arithmetic level raising for unitary groups of even rank. We will also mention other interesting results we obtained during the course of proof. This is based on a joint work with Y. Tian, L. Xiao, W. Zhang, and X. Zhu |

Tue Apr 09 |
## Special Events and Seminars11:00am - Vincent Hall 213Arithmetic level raising for unitary groups and Beilinson-Bloch-Kato conjecture (I) Yifeng Liu, Yale University In this series of two talks, we will introduce the recent progress on Beilinson-Bloch-Kato conjecture for Rankin-Selberg motives of arbitrary rank. We will discuss an important technique used in the proof, namely, the arithmetic level raising for unitary groups of even rank. We will also mention other interesting results we obtained during the course of proof. This is based on a joint work with Y. Tian, L. Xiao, W. Zhang, and X. Zhu. |

Fri Mar 15 |
## Special Events and Seminars2:30pm - Vincent Hall 1Mathematical Physics, Algebraic Geometry, and Commutative Algebra Nadia OttNadia Ott |

Thu Mar 14 |
## Special Events and Seminars1:25pm - Vincent Hall 113Nearby cycles over general bases and duality Weizhe Zheng, Chinese Academy of Sciences and Princeton University Over one-dimensional bases, Gabber and Beilinson proved theorems on the commutation of the nearby cycle functor and the vanishing cycle functor with duality. In this talk, I will explain a way to unify the two theorems, confirming a prediction of Deligne. I will also discuss the case of higher-dimensional bases and applications to local acyclicity, following suggestions of Illusie and Gabber. This is joint work with Qing Lu. |

Tue Mar 12 |
## Special Events and Seminars11:00am - Vincent 213Compatible systems along the boundary Weizhe Zheng, Chinese Academy of Sciences and Princeton University A theorem of Deligne says that compatible systems of l-adic sheaves on a smooth curve over a finite field are compatible along the boundary. I will present an extension of Deligne's theorem to schemes of finite type over the ring of integers of a local field. This has applications to the equicharacteristic case of some conjectures on l-independence. I will also discuss the relationship with compatible wild ramification. This is joint work with Qing Lu. |

Fri Feb 15 |
## Special Events and Seminars3:35pm - Vincent Hall 313Fontaine-Mazur conjecture in the residually reducible case (II) Lue Pan, University of Chicago We prove the modularity of some two-dimensional residually reducible p-adic Galois representations over Q when p is at least 5. In the first talk, I will present a generalization of Emerton's local-global compatibility result. In the second talk, I will use this compatibility result to make a patching argument for completed homology in this setting. |

Thu Feb 14 |
## Special Events and Seminars1:25pm - Vincent Hall 113Fontaine-Mazur conjecture in the residually reducible case (I) Lue Pan, University of Chicago We prove the modularity of some two-dimensional residually reducible p-adic Galois representations over Q when p is at least 5. In the first talk, I will present a generalization of Emerton's local-global compatibility result. In the second talk, I will use this compatibility result to make a patching argument for completed homology in this setting. |

Mon Dec 10 |
## Special Events and Seminars3:35pm - Vincent Hall 207Optimal transport on graphs with Applications Wuchen LiWuchen Li In recent years, optimal transport has many applications in evolutionary dynamics, statistics, and machine learning. In this talk, we introduce dynamical optimal transport on finite graphs. We proposed to study the probability simplex as a Riemannian manifold with a Wasserstein metric. We call it a probability manifold. Various developments, especially the Fokker-Planck equation, will be introduced. The entropy production on graphs related to Shannon entropy will be established. Its connection with Fisher information and Yanos formula will be studied. Many examples, including Mean field games, geometry of graphs, statistical learning problems, will be presented. |

Thu Dec 06 |
## Special Events and Seminars11:00am - Tate Hall B20p-adic local systems in p-adic geometry Koji Shimizu, University of California, Berkeley An etale p-adic local system on a rigid analytic variety can be regarded as a family of p-adic Galois representations parametrized by the variety, and p-adic Hodge theory has brought many results and applications on such objects, including a p-adic Riemann-Hilbert correspondence by Diao, Lan, Liu and Zhu. I will discuss constancy of a key invariant (generalized Hodge-Tate weights) of general p-adic local systems |

Mon Nov 26 |
## Special Events and Seminars3:35pm - Vincent Hall 207Inverse transport theory and related applications Ru-Yu Lai, University of Minnesota The inverse transport problem consists of reconstructing the optical properties of a medium from boundary measurements. It finds applications in a variety of fields. In particular, radiative transfer equation (a linear transport equation) models the photon propagation in a medium in optical tomography. In this talk I will address results on the determination of these optical parameters. Moreover, the connection between the inverse transport problem and the Calderon problem will also be presented. |

Thu Nov 08 |
## Special Events and Seminars1:25pm - Vincent Hall 313Irreducible components of affine Deligne--Lusztig varieties and orbital integrals Rong Zhou, Institute for Advanced Study Affine Deligne--Lusztig varieties (ADLV) naturally arise in the study of Shimura varieties and Rapoport--Zink spaces. Their irreducible components provide an interesting class of cycles on the special fiber of Shimura varieties. We prove a conjecture of Miaofen Chen and Xinwen Zhu, which relates the number of irreducible components of ADLV's to a certain weight multiplicity for a representation of the Langlands dual group. Our approach is to count the number of F_q points as q goes to infinity; this boils down to computing a certain twisted orbital integral. After applying techniques from local harmonic analysis, we reduce to computing a particular coefficient of the matrix for the inverse Satake transform. Using an interpretation of this coefficient in terms of a q-analogue of Kostant's partition function, we are able to reduce the problem to the previously known special cases of the conjecture proved by Hamacher--Viehmann and Nie. This is joint work with Yihang Zhu. |

Thu Oct 04 |
## Special Events and Seminars1:25pm - Vincent Hall 313The Langlands-Kottwitz-Scholze method for Shimura varieties of abelian type Alex Youcis, University of California, Berkeley The local (and global) Langlands conjectures attempt to bridge the major areas of harmonic analysis and number theory by forming a correspondence between representations which naturally appear in both areas. A key insight due to Langlands and Kottwitz is that one could attempt to understand such a conjectural correspondence by comparing the traces of natural operators on both sides of the bridge. Moreover, it was realized that Shimura varieties present a natural means of doing this. For global applications, questions of reduction type (at a particular prime p) for these Shimura varieties can often be avoided, and for this reason the methods of Langlands and Kottwitz focused largely on the setting of good reduction. But, for local applications dealing with the case of bad reduction is key. The setting of bad reduction was first dealt with, for some simple Shimura varieties, by Harris and Taylor which they used, together with the work of many other mathematicians, to prove the local Langlands conjecture for GL_n. A decade later Scholze gave an alternative, more geometric, way to understand the case of bad reduction for certain Shimura varieties and was able to reprove the local Langlands conjecture for GL_n. In this talk we will discuss an extension of the ideas of Scholze to a wider class of Shimura varieties, as well as the intended application of these ideas to the local Langlands conjectures for more general groups. |

Thu Aug 02 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Tue Jul 31 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Thu Jul 26 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Tue Jul 24 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Thu Jul 19 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Tue Jul 17 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Thu Jul 12 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Tue Jul 10 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Thu Jul 05 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Tue Jul 03 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Thu Jun 28 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Tue Jun 26 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Thu Jun 21 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Tue Jun 19 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Thu Jun 14 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Tue Jun 12 |
## Special Events and Seminars3:00pm - Vincent Hall 301Representation Theory Seminar TBATBA |

Tue May 01 |
## Special Events and Seminars8:30am - Vincent Hall 570Senior Honors Presentations Senior Honors PresentationsSenior Honors Presentations 8:30- 8:50, Owen Levin, working title "Approximation Algorithms for Network Connectivity," adviser Everyone welcome. Honors undergraduate math students present a short account of their work. |

Thu Apr 26 |
## Special Events and Seminars9:00am - Vincent Hall 570Senior Honors Presentations Senior Honors PresentationsSenior Honors Presentations 9-9:20, Kelly Catlin, "Finding an Optimal Velocity for a Race" , adviser Professor Mori Everyone welcome. Honors undergraduate math students present a short account of their work. |

Tue Apr 24 |
## Special Events and Seminars2:30pm - Ford Hall 130Cyclic Groups and Partitions Ashleigh AdamsAshleigh Adams A partition is a way of writing n as the sum of positive integers. While working in the cyclic of the finite group order n, it is possible to partition the entire group into a fixed size such that the partitions are equivalent to 0 modulo n. Since there is a direct bijective correspondence between Young Diagrams, cyclic partitions, and Gaussian binomial coefficients, it will be show that these box-partitions can be counted by the sum of specific coefficients within the Gaussian binomial coefficients. |

Tue Apr 17 |
## Special Events and Seminars2:30pm - Ford Hall 130Quivers, Representations, and Gabriel's Theorem Nick WhiteNick White Gabriels theorem states that a connected quiver has finite representation type if and only if its underlying graph has Dynkin type A, D, or E, and that for such quivers, the isoclasses of indecomposable representations are in bijection with the positive roots of the quivers associated quadratic form. The goal of this talk is to introduce some results that motivate Gabriels theorem and give an overview of the proof. Along the way, I will develop some language to talk about representations, including short exact sequences and projective resolutions. |

Tue Apr 03 |
## Special Events and Seminars2:30pm - Ford Hall 130Iterative Methods for Computing Square Roots Meir JablonMeir Jablon We will be discussing Iterative methods for computing square roots. Methods from different historical time periods will be introduced. Also, fixed point algorithms will be discussed at length. |

Thu Mar 29 |
## Special Events and Seminars4:45pm - Vincent Hall 364On certain special values of L-functions associated to elliptic curves and real quadratic fields Chung Pang Mok, Purdue University We study certain normalized special values of L-functions associated to elliptic curves and real quadratic fields. Under certain hypothesis, we are able to show that these are squares of rational numbers. This result can be regarded as instances of the rank zero case of the Birch and Swinnerton-dyer conjecture modulo squares, and is related to a theorem of Bertolini-Darmon on rationality of Stark-Heegner points over genus fields of real quadratic fields. |

Tue Mar 27 |
## Special Events and Seminars2:30pm - Ford Hall 130The Poisson Process and Phylogenetic Trees Mansi BezbaruahMansi Bezbaruah A phylogenetic tree is a visual representation of the relationship between different organisms, showing the path through evolutionary time from a common ancestor to different descendants. It is hypothesized that the growth of uniform pure-birth Phylogenetic Trees can be simulated by a Poisson growth. This project is an exploration into the expectations of a Poisson-directed growth of Phylogenetic Trees. |

Tue Mar 20 |
## Special Events and Seminars2:30pm - Ford Hall 130How Quick is a Cookie Random Walk? Owen LevinOwen Levin Cookie Random Walks are a discrete model for self-interacting random motion. At each time step, the transition probabilities to the next site depend on how many times the walker has visited its current location. In this talk, we will explore the limiting speed of such walks, which is a fancy way of saying the average ratio of the distance from the origin versus the time it took to get there. The goal of this talk is to give intuition for how one might try to analyze this speed starting from basic principles. I will try to assume little to no previous experience with the topics discussed. |

Tue Mar 06 |
## Special Events and Seminars2:30pm - Ford Hall 130Grammar Induction: Unsupervised Learning for Natural Language - Canceled Eishani KumarEishani Kumar Language parsers are traditionally are built around a large corpora of marked up text. While they can be generated semi-automatically, treebanks for natural language still must be manually reviewed and thus requires large amounts of time and expertise to create. Grammar induction attempts to find the hierarchical structure of a given language in a unsupervised manner, eliminating the need of this expensive labor. Here we discuss the current research involved in grammar induction, its limitations, and multilingual applications for this technology. |

Mon Feb 19 |
## Special Events and Seminars2:30pm - Vincent Hall 20Dynamical Systems Seminar - Title: Bifurcations in a Model for Vegetation Patterns Jasper Weinburd, University of Minnesota We use bifurcation theory to explore a simple model for migrating vegetation bands as observed on gradual slopes of semi-arid grasslands. Our model reproduces this behavior with minimal complexity and mathematically explains the uphill motion. In our analysis we examine the traveling-wave ODE, which turns out to be a tutorial on classic geometric techniques, despite its simplicity. We will focus on the rich bifurcation diagram that results and mention where one could also use methods such as invariant-region phase plane analysis, geometric blow-up, and singular perturbation theory. |

Fri Feb 16 |
## Special Events and Seminars3:45pm - Tate Hall 101Nonoverlapping Domain Decomposition Methods for Saddle Point Problems Xuemin TuXuemin Tu In this talk, two most popular nonovelapping domain decomposition algorithms will be discussed for solivng a class of saddle point problems arising from mixed finite element or hybridizable discontinuous Galerkin discretizations of partial differential equations. These algorithms reduce the original |

Tue Feb 13 |
## Special Events and Seminars2:30pm - Ford Hall 130Undergraduate Mathematics Research Seminar - EMD and Chaos John NguyenJohn Nguyen We explore the effectiveness of a time series algorithm in studying chaotic systems. First we study the effect of forcing on an oceanic model. After the model exhibits chaotic behavior, our focus will shift towards classical chaotic systems and a method of time series signal decomposition tool called the Hilbert-Huang transform. After analyzing decompositions of systems such as the Duffing oscillator and the Lorenz attractor, we end our discussion with an evaluation of the Hilbert-Huang transform. |

Tue Jan 30 |
## Special Events and Seminars2:30pm - Ford Hall 130Constraints on the Oceanic Carbon Sink Using Atmospheric Oxygen Data Julie ShermanJulie Sherman In this study we develop a simple model of the global carbon-oxygen budget in which we incorporate data from the Scripps Carbon Dioxide and Oxygen Programs. Our results are obtained from derivative free optimization techniques, and give minimum sources and sinks necessary to replicate atmospheric observations. We compare our results to large and complex global circulation models. |