Calendar
Posted November 12, 2025
Mathematical Physics and Representation Theory Seminar
1:30 pm – 2:20 pm Lockett 233
Iain Moffatt, Royal Holloway, University of London
Hypermap minors
As mathematicians we conventionally model networks as graphs. In a graph, each edge has exactly two ends, each lying on a vertex. Hypergraphs generalise graphs by allowing an edge to have any number of ends. As the edges of a hypergraph can connect any number of vertices, not just two, they offer a way to model higher-order interactions in networks. Graphs often arise in applications with the additional structure of an embedding in a surface. This is also happens for hypergraphs: a hypermap is a hypergraph embedded in a closed surface. This talk is about hypermaps. I'll begin by reviewing the basics of hypermaps, including various ways to describe them. I'll go on to present a theory of hypermap minors based upon a smoothing operation in cubic graphs. I'll discuss various aspect of this theory such as commutativity, duality and Tutte's triality, polynomials, and relations with Farr's theory of alternating dimaps. This is joint work with Jo Ellis-Monaghan and Steven D. Noble.
Posted November 13, 2025
Last modified November 16, 2025
Colloquium Questions or comments?
3:30 pm 232 Lockett Hall
Sky Cao, Massachusetts Institute of Technology
Yang-Mills, probability, and stochastic PDE
Originating in physics, Yang-Mills theory has shaped many areas of modern mathematics. In my talk, I will present Yang-Mills theory in the context of probability, highlighting central questions and recent advances. In particular, I will discuss the role of stochastic partial differential equations (SPDEs) in these developments and survey some of the recent progress in this field.
Posted November 15, 2025
Algebra and Number Theory Seminar Questions or comments?
2:00 pm – 3:00 pm Lockett 233 or click here to attend on Zoom
Esme Rosen, Louisiana State University
TBA
TBA
Posted November 13, 2025
Last modified November 17, 2025
Colloquium Questions or comments?
3:30 pm 232 Lockett Hall
Mengxuan Yang, Princeton University
Flat bands in 2D materials
Magic angles are a hot topic in condensed matter physics: when two sheets of graphene are twisted by these angles, the resulting material is superconducting and the so-called energy bands are flat and topological. In 2011, Bistritzer and MacDonald proposed a model that is experimentally very accurate in predicting magic angles. In this talk, I will introduce some recent mathematical progress on the Bistritzer--MacDonald's model, including the mathematical characterization of magic angles and flat bands, the generic existence of Dirac cones and how topological phase transitions occur at magic angles. I will also discuss some new mathematical discoveries in twisted multilayer graphene.
Posted November 13, 2025
Last modified November 23, 2025
Colloquium Questions or comments?
3:30 pm 232 Lockett Hall
Peter Bradshaw, University of Illinois Urbana-Champaign
Toward Vu's conjecture
In 2002, Vu conjectured that graphs of maximum degree $\Delta$ and maximum codegree at most $\zeta \Delta$ have chromatic number at most $(\zeta+o(1))\Delta$. Despite its importance, the conjecture has remained widely open. The only direct progress so far has been obtained in the "dense regime,'' when $\zeta$ is close to $1$, by Hurley, de Verclos, and Kang.
In this talk, I will discuss one of my recent results achieving the first major progress in the sparse regime where \zeta approaches 0, the case of primary interest to Vu. The result states that there exists $\zeta_0 > 0$ such that for all $\zeta \in [\log^{-32}\Delta,\zeta_0]$, the following holds: if $G$ is a graph with maximum degree $\Delta$ and maximum codegree at most $\zeta \Delta$, then $\chi(G) \leq (\zeta^{1/32} + o(1))\Delta$. This bound is derived from a more general result that assumes only that the common neighborhood of any $s$ vertices is bounded rather than the codegrees of pairs of vertices. The more general result also extends to the list coloring setting, which is of independent interest.
This talk is based on joint work with Dhawan, Methuku, and Wigal.
Posted September 10, 2025
Last modified September 23, 2025
Geometry and Topology Seminar Seminar website
3:30 pm Lockett 233
Corey Bregman, Tufts University
TBA
TBA
Posted August 27, 2025
Last modified November 26, 2025
Informal Geometry and Topology Seminar Questions or comments?
3:30 pm Lockett Hall 233
Krishnendu Kar, Louisiana State University
Khovanov Homology
Wrapping up our discussion on Khovanov Homology from this semester.
Posted November 12, 2025
Colloquium Questions or comments?
3:30 pm Lockett 232
Iain Moffatt, Royal Holloway, University of London
Graphs in surfaces, their one-face subgraphs, and the critical group
Critical groups are groups associated with graphs. They are well-established in combinatorics; closely related to the graph Laplacian and arising in several contexts such as chip firing and parking functions. The critical group of a graph is finite and Abelian, and its order is the number of spanning trees in the graph, a fact equivalent to Kirchhoff’s Matrix--Tree Theorem.
What happens if we want to define critical groups for graphs embedded in surfaces, rather than for graphs in the abstract?
In this talk I'll offer an answer to this question. I'll describe an analogue of the critical group for an embedded graph. We'll see how it relates to the classical critical groups, as well as to Chumtov's partial-duals, Bouchet's delta-matroids, and a Matrix--quasi-Tree Theorem of Macris and Pule, and describe how it arises through a chip-firing process on graphs in surfaces.
This is joint work with Criel Merino and Steven D. Noble.
Posted July 22, 2025
Last modified November 13, 2025
Control and Optimization Seminar Questions or comments?
10:30 am – 11:20 am Zoom (click here to join)
Javad Velni, Clemson University
Optimal Supplemental Lighting in Controlled Environment Agriculture: Data-driven and Model-based Perspectives
This seminar presents one aspect of my lab’s research focused on developing optimal supplemental lighting control strategies using LED lamps in controlled environment agriculture. The work aims to minimize electricity costs associated with supplemental lighting by integrating model-based optimization techniques with advanced machine learning methods, such as deep neural networks and Markov chains, used to predict uncertain environmental variables. Several scenarios are explored, ranging from a baseline optimal lighting approach for a single crop to more complex settings involving large-scale greenhouses with multiple crops and spatial light distribution considerations. Experimental results from a research greenhouse, where an Internet of Agricultural Things (IoAT) system was developed to grow lettuce, are presented and discussed. The seminar concludes with a roadmap highlighting several emerging research directions inspired by these findings.
Posted November 13, 2025
Last modified November 16, 2025
Colloquium Questions or comments?
3:30 pm 232 Lockett Hall
Sean Cotner, University of Michigan
Propagating congruences in the local Langlands program
The Langlands program is a vast generalization of quadratic reciprocity, aimed at understanding the algebraic field extensions of the rational or p-adic numbers. In this talk, I will describe a biased and incomplete history of the classical local Langlands program; recent developments in making it categorical, integral, and modular; and joint work-in-progress with Tony Feng concerned with patching together the modular theory to understand the classical theory.
Posted August 18, 2025
Control and Optimization Seminar Questions or comments?
10:30 am – 11:20 am Zoom (click here to join)
Zequn Zheng, Louisiana State University
TBA
Posted November 5, 2025
1:00 pm – 4:00 pm Lockett Hall 232Qualifier Exam in Algebra
Event contact: Stephen Shipman
Posted November 5, 2025
1:00 pm – 4:00 pm Lockett Hall 232Qualifier Exam in Analysis
Event contact: Stephen Shipman
Posted November 5, 2025
1:00 pm – 4:00 pm Lockett Hall 232Qualifier Exam in Topology
Event contact: Stephen Shipman
Posted November 5, 2025
1:00 pm – 4:00 pm Lockett Hall 232Qualifier Exam in Applied Math
Event contact: Stephen Shipman
Posted November 24, 2025
Informal Geometry and Topology Seminar Questions or comments?
1:30 pm Lockett Hall 233
Krishnendu Kar, Louisiana State University
Matthew Lemoine, Louisiana State University
Organizational Meeting
Join us for the first meeting of the Spring Semester 2026 Informal Geometry and Topology Seminar to decide which topic we will follow. The Informal Geometry and Topology Seminar is an opportunity for graduate students to get experience presenting information that they learn or have learned. We normally have a topic, paper, book, or subject that we follow and take turns presenting the information we learn, or giving independent talks about our own research. If you have any questions or would like to be added to the email list, please feel free to email Matthew Lemoine (mlemo36@lsu.edu) or Krishnendu Kar (kkar2@lsu.edu).
Posted November 15, 2025
Algebra and Number Theory Seminar Questions or comments?
2:00 pm – 3:00 pm Lockett 233 or click here to attend on Zoom
Olivia Beckwith, Tulane University
TBA
TBA
Posted November 22, 2025
Last modified November 23, 2025
Control and Optimization Seminar Questions or comments?
9:30 am – 10:20 am Zoom (click here to join)
Henk van Waarde, University of Groningen
IEEE L-CSS Outstanding Paper and SIAM SIAG/CST Prize Awardee
TBA
Posted November 26, 2025
Control and Optimization Seminar Questions or comments?
9:30 am – 10:20 am Zoom (click here to join)
Anthony Bloch, University of Michigan
AMS, IEEE, and SIAM Fellow
TBA
Posted November 15, 2025
Algebra and Number Theory Seminar Questions or comments?
2:00 pm – 3:00 pm Lockett 233 or click here to attend on Zoom
Marco Sangiovanni Vincentelli, Columbia University
TBA
TBA
Posted September 3, 2025
1:00 pm – 4:00 pm Saturday, March 7, 2026 Digital Media Center TheatreScientific Computing Around Louisiana (SCALA) 2026
Posted November 15, 2025
Algebra and Number Theory Seminar Questions or comments?
2:00 pm – 3:00 pm Lockett 233 or click here to attend on Zoom
Kiran Kedlaya, University of California, San Diego
TBA
TBA