Published on Department of Mathematics (https://math.yale.edu)

Week of October 10, 2021

October 11, 2021
Geometry, Symmetry and Physics	The sup norm-problem, Hecke eigensheaves, and the polar multiplicities of the nilpotent cone	Will Sawin - Columbia University	4:30pm - Zoom

October 12, 2021
Geometry & Topology	Tropical Fock-Goncharov coordinates for SL3-webs on surfaces - Part 2	Daniel Douglas - Yale University	4:15pm - LOM 214

October 13, 2021
Applied Mathematics	On the topic of topic modeling: enhancing machine learning approaches with topic features"	Deanna Needell - UCLA	2:30pm - https://yale.zoom.us/j/2188028533
Undergraduate Seminar	Putnam Seminar	Pat Devlin - Yale	4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214
Colloquium	Billiards, geometry, and symbolic coding	Chris Leininger - Rice University	4:15pm -

October 14, 2021
Algebra and Geometry lecture series	Quantizations in charateristic p. Lecture 6	Ivan Losev - Yale	4:00pm - https://yale.zoom.us/j/99019019033 (password was emailed by Ivan)
Analysis	Long-time dynamics of 1d cubic nonlinear Schrödinger equations with a trapping potential	Gong Chen - University of Toronto	4:15pm -

October 15, 2021
Geometric Analysis and Application	Stable minimal hypersurfaces in R^4	Otis Chodosh - Stanford University	2:00pm -
Social events	Math Bike Riding Event		3:30pm - DL - 10 Hillhouse

Abstracts

Week of October 10, 2021

October 11, 2021
Geometry, Symmetry and Physics	The sup norm-problem, Hecke eigensheaves, and the polar multiplicities of the nilpotent cone	4:30pm - Zoom	Abstract: This talk will discuss two closely-related geometric questions about the moduli space of vector bundles on an algebraic curve and its cotangent bundle, the moduli space of Higgs bundles. One involves computing some intersection-theoretic invariants of the nilpotent cone and the other involves understanding the stalks of the Hecke eigensheaves on this moduli space defined in the geometric Langlands program. The motivation for these problems comes from classical number theory and the relationship between the two passes through a new characteristic p version of a general theorem of Massey. The talk will give an overview of all these aspects. Zoom link: https://yale.zoom.us/j/99305994163, contact the organizers (Gurbir Dhillon and Junliang Shen) for the passcode.

October 12, 2021
Geometry & Topology	Tropical Fock-Goncharov coordinates for SL3-webs on surfaces - Part 2	4:15pm - LOM 214	This is a continuation of the 10/05 talk.

October 13, 2021
Applied Mathematics	On the topic of topic modeling: enhancing machine learning approaches with topic features"	2:30pm - https://yale.zoom.us/j/2188028533	Abstract: In this talk we touch on several problems in machine learning that can benefit from the use of topic modeling. We present topic modeling based approaches for online prediction problems, computer vision, text generation, and others. While these problems have classical machine learning approaches that work well, we show that by incorporating contextual information via topic features, we obtain enhanced and more realistic results. These classical methods include non-negative matrix and tensor factorization, generative adversarial networks, and even traditional epidemiological SIR models for prediction. In this talk we provide a brief overview of these problems and show how topic features can be used in these settings. We include supporting theoretical and experimental evidence that showcases the broad use of our approaches.
Undergraduate Seminar	Putnam Seminar	4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214 , 4:00pm - LOM 214	The Putnam seminar meets every Wednesday from 4 to 5:30 in LOM 214. As always, everyone is warmly welcomed to come to hang out, learn more cool math, and meet folks. The seminar is casual, and folks can come and go as they like. See Pat Devlin’s webpage (and/or contact him) for more information. Folks can sign up for the mailing list here: https://forms.gle/nYPx72KVJxJcgLha8
Colloquium	Billiards, geometry, and symbolic coding	4:15pm -	Abstract: Given a polygon in the Euclidean or hyperbolic plane, its billiard flow on the tangent bundle has trajectories that describe the paths of particles in the polygon (the billiard trajectories) traveling along straight lines and “bouncing” off the sides. Labeling the sides of the polygon the billiard flow determines a symbolic coding we call the bounce spectrum, which is the set of biinfinite sequences of labels corresponding to the sides encountered by all trajectories. A natural question asks the extent to which the bounce spectrum determines the shape of the polygon. For both Euclidean and hyperbolic polygons, there are nontrivial constructions of polygons with the same bounce spectrum that are not isometric/similar. In this talk, I’ll describe these constructions, and then results of joint work with Duchin, Erlandsson, and Sadanand stating that these are in fact the only ways in which non-isometric/non-similar polygons can have the same bounce spectrum.

October 14, 2021
Algebra and Geometry lecture series	Quantizations in charateristic p. Lecture 6	4:00pm - https://yale.zoom.us/j/99019019033 (password was emailed by Ivan)	This is the sixth lecture in the series. Details can be found here: Algebra and Geometry lecture series (yale.edu)
Analysis	Long-time dynamics of 1d cubic nonlinear Schrödinger equations with a trapping potential	4:15pm -	Abstract: We will consider the long-time dynamics of small solutions to the 1d cubic nonlinear Schrödinger equation (NLS) with a trapping potential. I will illustrate that every small solution decomposes into a small solitary wave and a radiation term which exhibits modified scattering. The analysis also establishes the long-time behavior of solutions to a perturbation of the integrable cubic NLS with the appearance of solitons.

October 15, 2021
Geometric Analysis and Application	Stable minimal hypersurfaces in R^4	2:00pm -	Abstract: I will explain why a two-sided stable minimal hypersurface in R^4 is flat. This is joint work with Chao Li.
Social events	Math Bike Riding Event	3:30pm - DL - 10 Hillhouse	Come join the math department for a Friday afternoon bike ride. We’ll leave from outside of DL (10 Hillhouse) at 3:30pm on Friday 10/15 and take an easy ride up the canal trail. All riders welcome; hope to see you there! -Math Department Climate Committee