Calendar
Posted February 17, 2026
12:30 pm – 1:30 pm Keisler Lounge
Laura Kurtz, Louisiana State University
Rerun: Accesibility in LaTeX Workshop
Learn how to make your LaTeX documents readable by screen readers.
Posted February 3, 2026
Mathematical Physics and Representation Theory Seminar
1:30 pm – 2:20 pm Lockett 233
Karl-Hermann Neeb, Universität Erlangen-Nürnberg
Coadjoint orbits carrying Gibbs ensembles
Coadjoint orbits are orbits for the action of a Lie group on the dual of its Lie algebra. They carry a natural symplectic structure and are models for homogeneous systems in classical mechanics. Gibbs measures on these orbits provide a natural setting for models of thermodynamic systems. We say that a coadjoint orbit carries a Gibbs ensemble if the set of all $x$, for which the function $\alpha \mapsto e^{-\alpha(x)}$ on the orbit is integrable with respect to the Liouville measure, has non-empty interior $\Omega_\lambda$. We describe a classification of all coadjoint orbits with this property. In the context of Souriau's Lie group thermodynamics, the subset $\Omega_\lambda$ is the geometric temperature, a parameter space for a family of Gibbs measures on the coadjoint orbit. The corresponding Fenchel--Legendre transform maps $\Omega_\lambda$ (modulo central shifts) diffeomorphically onto the interior of the convex hull of the coadjoint orbit $\cO_\lambda$. This provides an interesting perspective on the underlying information geometry.
Posted November 15, 2025
Last modified January 21, 2026
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
An Euler system for the adjoint of a modular form
Euler systems have proven to be versatile tools for understanding Selmer groups and their connections to special values of $L$-functions. However, despite the key role they have played in making progress toward foundational conjectures in number theory, such as the Birch and Swinnerton-Dyer and Bloch–Kato Conjectures, only a handful of provably non-trivial Euler systems have been constructed to date. A significant obstacle to constructing Euler Systems lies in producing candidate Galois cohomology classes. This lecture series presents joint work with Chris Skinner that develops a method to overcome this obstacle. Using this method, we construct an Euler system for the adjoint of a modular form.
Event contact: Gene Kopp
Posted February 6, 2026
5:30 pm Lockett HallASA Excel Workshop
We will be joined by our SOA Liason Matthew who will continue his Excel Workshop from last year! Pizza Will be Served
Posted February 9, 2026
Last modified February 23, 2026
Informal Analysis Seminar Questions or comments?
12:30 pm – 1:30 pm Lockett 233
Gustavs Tobiss, Louisiana State University
Bloch's Theorem, Wannierization, and Tight-binding
This talk presents the mathematical framework and numerical methods behind tight-binding models for electrons in a one-dimensional periodic potential, focusing on the transition from Bloch states to Wannier functions. We start by revisiting Bloch’s theorem, which leads to a decomposition into independent Hamiltonians for each wavevector in the Brillouin zone. This immediately allows us to describe the system in terms of its band structure. We then introduce Wannier functions, localized eigenstates derived from band eigenfunctions. The Wannier functions possess many nice qualities, such as being exponentially localized and orthonormal, with the decay tied to the analyticity of the band structure. Next, we derive the tight-binding Hamiltonian by projecting onto a single band subspace. This Hamiltonian is expressed as a sum of hopping terms, with hopping amplitudes related to the band structure, providing a link to the system's dispersion relation and physical properties. Finally, we discuss how this simple model will be used to analyze more complicated structures.
Posted January 28, 2026
Last modified February 17, 2026
Geometry and Topology Seminar Seminar website
1:30 pm 233 Lockett Hall
Nir Gadish, University of Pennsylvania
Letter braiding invariants of words in groups
How can we tell if a group element can be written as k-fold nested commutator? One way is to find a collection of computable function that vanish only on nested commutators. This talk will introduce letter-braiding invariants - these are elementarily defined functions on words, inspired by the homotopy theory of loop-spaces and carrying deep geometric content. They give a universal finite-type invariant for arbitrary groups, extending the influential Magnus expansion of free groups that already had countless applications in low dimensional topology. As a consequence we get new geometric formulas for braid and link invariants, and a way to linearize automorphisms of general groups that specializes to the Johnson homomorphism of mapping class groups.
Posted January 15, 2026
Last modified February 20, 2026
Informal Geometry and Topology Seminar Questions or comments?
3:30 pm – 4:30 pm Lockett Hall 233
Hailey Garcia, Louisiana State University
The Cohomology of the Complement of Hyperplane Arrangements
We consider linear hyperplane arrangements 𝓐 in V=ℂ^n. Of interest is the complement of the arrangement M(𝓐)=M(𝓐)=V\(∪_{H_i∈𝓐}H_i). We will demonstrate the definition and some properties of the Orlik-Solomon algebra A(𝓐) of 𝓐. Then, by considering the deletion-restriction triple (𝓐',𝓐,𝓐''), we demonstrate that the cohomology ring of M(𝓐) is isomorphic to A(𝓐) and hence determined by the combinatorics of the intersection lattice L(𝓐).
Posted January 8, 2026
Control and Optimization Seminar Questions or comments?
9:30 am – 10:20 am Zoom (click here to join)
Lars Gruene, University of Bayreuth
SIAM Fellow
Can Neural Networks Solve High Dimensional Optimal Feedback Control Problems?
Deep reinforcement learning has established itself as a standard method for solving nonlinear optimal feedback control problems. In this method, the optimal value function (and, in some variants, the optimal feedback law also) is stored using a deep neural network. Hence, the applicability of this approach to high-dimensional problems relies crucially on the network's ability to store a high-dimensional function. It is known that for general high-dimensional functions, neural networks suffer from the same exponential growth of the number of coefficients as traditional grid based methods, the so-called curse of dimensionality. In this talk, we use methods from distributed optimal control to describe optimal control problems in which this problem does not occur.
Posted February 9, 2026
LSU AWM Student Chapter LSU AWM Student Chapter Website
12:30 pm the Keiser Lounge, Lockett Hall 3rd floorDiscussion session with Amber Schreve
The AWM Student Chapter is pleased to host a special discussion session with Amber Schreve, a PhD student in Finance at LSU and an actuary at the Louisiana Department of Insurance. She will share her experience as a mathematician working in the actuarial field, discussing her journey from studying mathematics to becoming an actuary. This offers a great opportunity for students to interact with Amber and ask questions about her career motivations and professional path behind transitioning from academia to industry.
Event contact: jgarc86@lsu.edu
Posted February 24, 2026
Combinatorics Seminar Questions or comments?
2:30 pm – 3:30 pm Zoom (click here to join)
Steven Noble, University of Leeds
Critical groups for embedded graphs
Critical groups are finite Abelian groups associated with graphs. They arise in many different ways, for example, via the chip-firing game, through the Laplacian and via fundamental cycles and cocycles. Several results in the literature on critical groups only hold for planar graphs and their proofs rely on a plane drawing. This suggests the natural setting for the critical group might be graphs embedded on surfaces. We show how various definitions of the critical group may be extended to embedded graphs, and crucially that they give isomorphic groups. No knowledge of topology or group theory is required!
Posted February 28, 2026
Probability Seminar Questions or comments?
1:00 pm – 2:00 pm Zoom
Leo Tyrpak, University of Oxford
Fluctuations of spatial population models with non-local interactions
We analyse a class of spatial population models where the branching rate of particles depends non-locally on the whole empirical measure of particles. Scaling limits of this model have previously been shown to include the non-local Fisher-KPP equation and the porous medium equation. In this talk we will discuss the fluctuations of the process around these deterministic limits. We will show how an understanding of these can be applied to quantify the impact on geographical distance on genetic distance in the spirit of the classical Wright-Malecot formula.
Posted February 10, 2026
Mathematical Physics and Representation Theory Seminar
1:30 pm – 2:20 pm Lockett 233
Milo Moses, Caltech
Four-colorings, recoverability, and topological quantum matter
In ongoing joint work with A. Kitaev, D. Ranard, I. Kim, we have been developing a formalism for exploring topologically ordered quantum states using recovery maps. In this talk, I will explain the potential applicability of these recovery maps to the study of 4-colorings of planar graphs. Conditioned on an unproven technical lemma (which perhaps someone in the audience can demonstrate!), I can show that bridgeless planar graphs quasi-isometric to the Euclidean plane obey a medley of properties reminiscent of topological quantum order.
Posted February 9, 2026
Informal Analysis Seminar Questions or comments?
12:30 pm – 1:30 pm Lockett 233
Basit Abdulfatai, Louisiana State University
Dolapo Onifade, Louisiana State University
Introduction to deep adaptive sampling and physics informed neural networks
Posted January 19, 2026
Last modified March 3, 2026
Geometry and Topology Seminar Seminar website
1:30 pm Virtual
Ettore Marmo, Università degli Studi di Milano-Bicocca
Toric arrangements and Bloch-Kato pro-p groups
For every field K we can define a distinguished extension K^{sep} called its separable closure. The maximal pro-p quotient G_K(p) of the Galois group $G_K = Gal(K^{sep}/K)$ is called the maximal pro-p Galois group of K, many arithmetical properties of the field are encoded in the structure of this group. It is interesting to ask which pro-p groups can be realized as the maximal pro-p Galois group of some field. It is known that any such group must also satisfy a cohomological property called the Bloch-Kato property. In this talk we will discuss some families of pro-p groups arising as from toric arrangements and some techniques to study the Bloch-Kato property in this context. This talk is based on joint work with Th. Weigel and E. Delucchi.
Posted January 15, 2026
Last modified February 27, 2026
Informal Geometry and Topology Seminar Questions or comments?
3:30 pm – 4:30 pm Lockett Hall 233
Benjamin Appiah, Louisiana State University
An example of color evaluation in graphene diagrams.
In this talk, I will explore the concept of decorated ribbon graphs, graphene diagrams, and virtual links. Then introduce a novel coloring technique called color evaluation. I will conclude by discussing an example of how this color evaluation is invariant in virtual link, knot, and graphene diagrams.
Posted February 26, 2026
11:00 am – 12:30 pm Lockett Hall-Keisler Lounge
Harbir Antil, George Mason University
Malena Espanol, Arizona State University
A Lunch with SCALA Speakers
A lunch and informal discussion providing an opportunity to ask questions before SCALA.
Posted September 3, 2025
Last modified January 14, 2026
Scientific Computing Around Louisiana (SCALA) 2026
http://www.cct.lsu.edu/SCALA2026
Posted February 26, 2026
Combinatorics Seminar Questions or comments?
2:30 pm Lockett 233 (Simulcast via Zoom)
Zi-Xia Song, University of Central Florida
Dominating Hadwiger's Conjecture
A dominating $K_t$ minor in a graph $G$ is a sequence $(T_1,\cdots,T_t)$ of pairwise disjoint non-empty connected subgraphs of $G$, such that for $1 \leq i < j \leq t$, every vertex in $T_j$ has a neighbor in $T_i$. Replacing "every vertex in $T_j$" by "some vertex in $T_j$" retrieves the standard definition of a $K_t$ minor. The strengthened notion was introduced in 2024 by Illingworth and Wood, who asked whether every graph with chromatic number $t$ contains a dominating $K_t$ minor. This is a substantial strengthening of the celebrated Hadwiger's Conjecture, which asserts that every graph with chromatic number $t$ contains a $K_t$ minor. Sergey Norin referred to this question as the "Dominating Hadwiger's Conjecture" and believes it is likely false. In this talk, we present our recent work on the Dominating Hadwiger's Conjecture and discuss the key ideas of our results. Joint work with Michael Scully and Thomas Tibbetts.
Posted January 12, 2026
Last modified March 15, 2026
Applied Analysis Seminar Questions or comments?
1:30 pm Lockett Hall 233
Daniel Massatt, New Jersey Institute of Technology
Momentum Space Algorithm for Electronic Structure of Double-Incommensurate Trilayer Graphene
Moiré 2D materials are highly tunable through variables including twist angle, species of layers, and number of layers. Various configurations lead to useful physical phenomena and possible applications, including many-body physics such as correlated insulators and superconductivity. To understand many-body models, a careful single-particle model must first be constructed. For example in twisted bilayer graphene, the Bistritzer-MacDonald model is frequently used to capture magic-angle physics in twisted bilayer graphene. More complex geometries including double-incommensurate trilayers however become difficult to accurately quantify even in the single-particle regime. Here we present a momentum space algorithm for computing observables for double-incommensurate trilayers with rigorous error analysis compared to the real space tight-binding model. We include the closest equivalent observable to band structure that this structure seems to admits called the momentum local density of states, revealing the spectral features not captured by rougher models.
Event contact: Stephen Shipman
Posted March 5, 2026
Last modified March 9, 2026
Informal Analysis Seminar Questions or comments?
1:30 pm – 2:30 pm Lockett 233
Long Teng, LSU
Doubling Inequalities for Schrodinger operators with power growth potentials
TBD
Posted March 17, 2026
Geometry and Topology Seminar Seminar website
1:30 pm Virtual
Jonathan Fruchter, University of Bonn
Virtual homological torsion in low dimensions
A long-standing conjecture of Bergeron and Venkatesh predicts that in closed hyperbolic 3-manifolds, the amount of torsion in the first homology of finite-sheeted normal covers should grow exponentially with the degree of the cover as the covers become larger, at a rate reflecting the volume of the manifold. Yet no finitely presented residually finite group is known to exhibit such behaviour, and meaningful lower bounds on torsion growth are rare. In this talk I will explain how a particular two-dimensional lens offers a clearer view of some of the underlying mechanisms that create homological torsion in finite covers, and how they might relate to its growth. If time allows, I will also discuss how these ideas connect to the question of profinite rigidity: how much information about a group is encoded in its finite quotients.
Posted January 15, 2026
Informal Geometry and Topology Seminar Questions or comments?
3:30 pm – 4:30 pm Lockett Hall 233
Sayani Mukherjee, Louisiana State University
TBD
TBD
Posted December 1, 2025
Last modified March 5, 2026
Control and Optimization Seminar Questions or comments?
9:30 am – 10:20 am Zoom (click here to join)
Khai Nguyen, North Carolina State University
On the Structure of Viscosity Solutions to Hamilton–Jacobi Equations
This talk presents regularity results for viscosity solutions to a class of Hamilton-Jacobi equations arising from optimal exit-time problems in nonlinear control systems under a weak controllability condition. A representation formula for proximal supergradients, based on transported normals, is derived, with applications to optimality conditions, the propagation of singularities, and the Hausdorff measure of the singular set.
Posted March 16, 2026
Combinatorics Seminar Questions or comments?
2:30 pm – 3:30 pm Lockett 233 (Simulcast via Zoom)
Weihao Xia, Louisiana State University
An improved $\chi$-binding function for chair-free graphs
We show that if a graph \(G\) does not contain the chair (the graph obtained from \(K_{1,3}\) by subdividing an edge once) as an induced subgraph, then its chromatic number satisfies \(\chi(G) \leq \omega(G)^2\), where \(\chi(G)\) and \(\omega(G)\) denote the chromatic number and clique number of \(G\), respectively. This result improves the recent upper bound of $7\omega(G)^2$ proved by Liu, Schroeder, Wang, and Yu [J. Combin. Theory Ser. B 162 (2021) 118--133].