Calendar
Calendar
Posted September 15, 2025
Combinatorics Seminar Questions or comments?
2:30 pm – 3:30 pm Zoom (click here to attend on Zoom)
Rose McCarty, Georgia Institute of Technology
Neighborhood complexity and matroids
Abstract: We will discuss neighborhood complexity in graphs and some of its many applications. We will touch on applications to graph coloring, discrete geometry, and first-order logic. However, our main focus will be using neighborhood complexity to find the "unavoidable" GF(q)-representable cosimple matroids of large girth. This talk is based on joint work with James Davies, Meike Hatzel, Kolja Knauer, and Torsten Ueckerdt.
Posted August 2, 2025
Last modified September 10, 2025
Algebra and Number Theory Seminar Questions or comments?
2:00 pm – 3:00 pm Lockett 233 or click here to attend on Zoom
Andreas Mono, Vanderbilt University
A modular framework for generalized Hurwitz class numbers
We discover a neat linear relation between the mock modular generating functions of the level $1$ and level $N$ Hurwitz class numbers. This relation gives rise to a holomorphic modular form of weight $\frac{3}{2}$ and level $4N$ for $N > 1$ odd and square-free. This follows from a more general inspection of the weight $\frac{1}{2}$ Maass–Eisenstein series of level $4N$v at its spectral point $s = \frac{3}{4}$. This idea goes back to Duke, Imamoğlu and Tóth in level $4$ and relies on the theory of so-called sesquiharmonic Maass forms. Furthermore, we connect the aforementioned results to a regularized Siegel theta lift as well as a regularized Kudla–Millson theta lift for odd prime levels, which builds on earlier work by Bruinier, Funke and Imamoğlu. This is joint work with Olivia Beckwith. We conclude by presenting the situation in higher weights as well, which is sole work.
Posted September 18, 2025
Informal Analysis Seminar Questions or comments?
3:30 pm – 4:30 pm Lockett 136
Matthew McCoy, Louisiana State University
Introduction to Ergodic Theory, Chebyshev Polynomial Expansions, and Schur Complements
This talk will serve as an introductory talk to Ken Beard's talk on 9/30: Momentum Space Algorithm for Electronic Structure of Double-Incommensurate Trilayer Graphene. We will introduce relevant concepts in spectral theory.
Event contact: Laura Kurtz
Posted September 1, 2025
Last modified September 18, 2025
Geometry and Topology Seminar Seminar website
3:30 am Lockett 233
Robin Koytcheff, University of Louisiana, Lafayette
Milnor invariants and thickness of spherical links
Various authors have studied the question of how long a rope of a given thickness is needed to tie a given isotopy class of knot or link. In joint work with Rafal Komendarczyk and Fedya Manin, we generalize this work to spherical links in arbitrary dimensions. In more detail, we study their Milnor invariants in terms of Massey products and prove asymptotically optimal upper bounds on Milnor invariants in terms of embedding thickness. Interestingly, there is a dichotomy between polynomial and exponential bounds, depending on the dimensions of the spheres. We apply our results to answer a question of Freedman and Krushkal about exponentially thin 2-complexes in 4-space.
Posted August 27, 2025
Informal Geometry and Topology Seminar Questions or comments?
1:30 pm Lockett Hall 233
Gargi Patil, Louisiana State University
TBD
TBD
Posted September 18, 2025
Informal Analysis Seminar Questions or comments?
3:30 pm – 4:30 pm Lockett 136
Ken Beard, LSU
Momentum Space Algorithm for Electronic Structure of Double-Incommensurate Trilayer Graphene
Although recent experimental results seem to indicate the existence of flat bands for twisted trilayer graphene (TTG), at present there is no convergent algorithm for approximating the density of states (or other desirable observables). We attempt to address this by using kernel polynomial approximation with an ab initio momentum-space tight-binding model. The unique challenge in the case of TTG is the lack of a periodic moir\'{e} supercell. This is addressed by modifying the truncation to account for more complex Umklapp scattering.
Event contact: Laura Kurtz
Posted September 10, 2025
Geometry and Topology Seminar Seminar website
3:30 am Lockett 233
Colin Crowley, University of Oregon
TBA
TBA
Posted August 27, 2025
Informal Geometry and Topology Seminar Questions or comments?
1:30 pm Lockett Hall 233
Saumya Jain, Louisiana State University
TBD
TBD (Independent Talk)
Posted August 14, 2025
Control and Optimization Seminar Questions or comments?
10:30 am – 11:20 am Zoom (click here to join)
Xin Zhang, New York University
TBA
Posted September 19, 2025
1:30 pm Lockett Hall ---
Jason Cantarella, University of Georgia
How and why to teach a computer to untangle knots
Unknot recognition is a classical 'hard problem' in computational topology. At the moment, the leading candidate for a full solution is Lackenby's quasi-polynomial algorithm which has theoretical complexity 2^(O(log n)^3). So far, this hasn't led to a really efficient practical method for knot identification. A different idea for knot simplification (knot energies) goes back to Freedman (and before). In this method, we try to put some energy function on a test curve such as a repulsive charge and then follow the evolution of the curve, hoping that it will lead to a recognizable configuration. This has proved to be computationally intractable for numerical reasons. In this talk, we describe a hybrid approach which alternates between using powerful diagrammatic simplifications and a new semigeometric energy defined on diagrams. We'll give results on benchmark sets of hard unknots and then discuss how this method allowed us to give strong new evidence supporting the 'knot entropy conjecture' for random knots in self-avoiding walks. This has consequences for knots in polymer chemistry and (perhaps) for knots in DNA and other biopolymers. The talk will include various animations and demonstrations, a couple of puzzles, and some open questions. It should be fairly accessible to undergraduates.
Posted March 28, 2025
Last modified September 15, 2025
Applied Analysis Seminar Questions or comments?
3:30 pm TBA
Wenxiong Chen , Yeshiva University
TBA
Event contact: Jiuyi Zhu
Posted March 16, 2025
Last modified September 15, 2025
Applied Analysis Seminar Questions or comments?
2:30 pm TBA
Nicola Garofalo, Arizona State University
Charles Wexler Professor in Mathematics,
TBA
Event contact: Jiuyi Zhu
Posted August 3, 2025
Last modified September 15, 2025
Applied Analysis Seminar Questions or comments?
3:30 pm TBA
Donatella Danielli, Arizona State University
School Director and Foundation Professor
TBA
Event contact: Jiuyi Zhu
Posted August 27, 2025
Informal Geometry and Topology Seminar Questions or comments?
1:30 pm Lockett Hall 233
Krishnendu Kar, Louisiana State University
TBD
TBD
Posted August 1, 2025
Control and Optimization Seminar Questions or comments?
10:30 am – 11:20 am Zoom (click here to join)
Felix Schwenninger, University of Twente, The Netherlands
TBA
Posted August 2, 2025
Algebra and Number Theory Seminar Questions or comments?
2:00 pm – 3:00 pm Lockett 233 or click here to attend on Zoom
Kenz Kallal, Princeton University
TBA
Posted August 27, 2025
Informal Geometry and Topology Seminar Questions or comments?
1:30 pm Lockett Hall 233
Adithyan Pandikkadan, Louisiana State University
TBD
TBD
Posted September 10, 2025
3:30 pm – 4:30 pm Lockett 138
Bruno Poggi, University of Pittsburgh
TBA
Posted August 27, 2025
Last modified September 12, 2025
Applied Analysis Seminar Questions or comments?
3:30 pm Lockett Hall 233
Xuenan Li, Columbia University
TBA: Something on 2D electronic materials
Event contact: Stephen Shipman
Posted September 2, 2025
Algebra and Number Theory Seminar Questions or comments?
2:00 pm Lockett 233 or click here to attend on Zoom
Guanyu Li, Cornell University
Derived Commuting Schemes, Representation Homology, and Cohomology of Lie Algebras
The commuting schemes of an algebraic group or a Lie algebra play important roles in many areas of mathematics. They can be viewed as special cases of representation schemes, which are often highly singular. Derived algebraic geometry provides tools to remedy the deficiency. In particular, the derived representation scheme, together with its associated algebraic invariant known as representation homology, offers deeper insights into the structure of representation schemes. While the representation homology of reductive groups and reductive Lie algebras has been studied in the literature, it is natural to ask about the behavior of these objects and their relationships in the non-reductive setting. In this talk, I will discuss the derived commuting scheme of a maximal unipotent subgroup of a semisimple group scheme, as well as the derived commuting scheme of its Lie algebra. First, the higher structure of the derived commuting scheme detects whether the underlying commuting scheme is a complete intersection. Unlike the reductive case, the derived commuting scheme of a unipotent subgroup is equivalent to that of its Lie algebra. Using an analogue of the trace map, most of the homology classes can be explained in terms of the classical cohomology of a maximal nilpotent Lie algebra, described via the root system of the semisimple Lie algebra. This could be interpreted that the singularities of the commuting scheme of a maximal nilpotent subalgebra are largely determined by root system data. If time permits, I will also discuss a possible nilpotent analogue of the Macdonald identity, together with an interpretation in terms of representation homology.
Posted September 1, 2025
Geometry and Topology Seminar Seminar website
3:30 am Lockett 233
Matthew Haulmark, UT Rio Grande Valley
TBA
TBA
Posted August 27, 2025
Informal Geometry and Topology Seminar Questions or comments?
1:30 pm Lockett Hall 233
Remi Mandal, Louisiana State University
TBD
TBD
Posted September 5, 2025
Control and Optimization Seminar Questions or comments?
10:30 am – 11:20 am Zoom (click here to join)
Naira Hovakimyan, University of Illinois Urbana-Champaign
Fellow of AIAA, ASME, IEEE, and IFAC
Safe Learning in Autonomous Systems
Learning-based control paradigms have seen many success stories with autonomous systems and robots in recent years. However, as these robots prepare to enter the real world, operating safely in the presence of imperfect model knowledge and external disturbances is going to be vital to ensure mission success. We introduce a class of distributionally robust adaptive control architectures that ensure robustness to distribution shifts and enable the development of certificates for validation and verification of learning-enabled systems. An overview of different projects at our lab that build upon this framework will be demonstrated to show different applications.
Posted September 9, 2025
Algebra and Number Theory Seminar Questions or comments?
2:00 pm – 3:00 pm Lockett 233 or click here to attend on Zoom
Kalani Thalagoda, Tulane University
A summation formula for Hurwitz class numbers
The Hurwitz class numbers, $H(n)$, count ${\rm SL}(2,\mathbb{Z})$-classes of binary quadratic forms inversely weighted by stabilizer size. They are famously connected to the sum of three squares problem and to class numbers of imaginary quadratic fields. The work of Zagier in 1975 showed that their generating functions are related to a weight $3/2$ Harmonic Maass form. In this talk, I will discuss a summation formula for mock modular forms of moderate growth, with an emphasis on its application to Hurwitz class numbers. This is joint work with Olivia Beckwith, Nicholas Diamantis, Rajat Gupta, and Larry Rolen.
Posted September 1, 2025
Last modified September 2, 2025
Geometry and Topology Seminar Seminar website
3:30 am Lockett 233
Chen Zhang, Stony Brook University
TBA
TBA
Posted August 27, 2025
Informal Geometry and Topology Seminar Questions or comments?
1:30 pm Lockett Hall 233
Nilangshu Bhattacharyya, Louisiana State University
TBD
TBD
Posted August 27, 2025
Informal Geometry and Topology Seminar Questions or comments?
1:30 pm Lockett Hall 233
Evan Short, Louisiana State University
TBD
TBD
Posted August 21, 2025
Geometry and Topology Seminar Seminar website
3:30 pm Lockett 233
Matthew Zaremsky, University at Albany (SUNY)
TBD
Posted August 19, 2025
Colloquium Questions or comments?
3:30 pm Lockett 232
David Roberts, University of Minnesota, Morris
TBA
Posted July 26, 2025
Control and Optimization Seminar Questions or comments?
10:30 am – 11:20 am Zoom (click here to join)
Rami Katz, Università degli Studi di Trento, Italy
Oscillations in Strongly 2-Cooperative Systems and their Applications in Systems Biology
The emergence of sustained oscillations (via convergence to periodic orbits) in high-dimensional nonlinear dynamical systems is a non-trivial question with important applications in control of biological systems, including the design of synthetic bio-molecular oscillators and the understanding of circadian rhythms governing hormone secretion, body temperature and metabolic functions. In systems biology, the mechanism underlying such widespread oscillatory biological motifs is still not fully understood. From a mathematical perspective, the study of sustained oscillations is comprised of two parts: (i) showing that at least one periodic orbit exists and (ii) studying the stability of periodic orbits and/or characterizing the initial conditions which yield solutions that converge to periodic trajectories. In this talk, we focus on a specific class of nonlinear dynamical systems that are strongly 2-cooperative. Using the theory of cones of rank k, the spectral theory of totally positive matrices and Perron-Frobenius theory, we will show that strongly 2-cooperative systems admit an explicit set of initial conditions of positive measure, such that every solution emanating from this set converges to a periodic orbit. We further demonstrate our results using the n-dimensional Goodwin oscillator and a 4-dimensional biological oscillator based on RNA–mediated regulation.
Posted August 21, 2025
Last modified September 13, 2025
Applied Analysis Seminar Questions or comments?
3:30 pm Lockett Hall 233
Roy Goodman, New Jersey Institute of Technology
TBA: Something on Hamiltonian systems
Event contact: Stephen Shipman
Posted September 1, 2025
Geometry and Topology Seminar Seminar website
3:30 am TBA
Jayden Wang, University of Michigan
TBA
TBA
Posted August 27, 2025
Informal Geometry and Topology Seminar Questions or comments?
1:30 pm Lockett Hall 233
Matthew Lemoine, Louisiana State University
TBD
TBD (Independent Talk)
Posted August 1, 2025
Control and Optimization Seminar Questions or comments?
10:30 am – 11:20 am Zoom (click here to join)
Thinh Doan, University of Texas at Austin
AFOSR YIP and NSF CAREER Awardee
TBA
Posted August 27, 2025
Informal Geometry and Topology Seminar Questions or comments?
1:30 pm Lockett Hall 233
Nilangshu Bhattacharyya, Louisiana State University
TBD
TBD
Posted July 13, 2025
Last modified July 18, 2025
Control and Optimization Seminar Questions or comments?
10:30 am – 11:20 am Zoom (click here to join)
Dimitra Panagou, University of Michigan
AFOSR YIP, NASA Early Career Faculty, and NSF CAREER Awardee
TBA
Posted August 27, 2025
Informal Geometry and Topology Seminar Questions or comments?
1:30 pm Lockett Hall 233
Huong Vo, Louisiana State University
TBD
TBD (Independent Talk)
Posted September 10, 2025
Geometry and Topology Seminar Seminar website
3:30 am Lockett 233
Corey Bregman, Tufts University
TBA
TBA
Posted August 27, 2025
Informal Geometry and Topology Seminar Questions or comments?
1:30 pm Lockett Hall 233
Krishnendu Kar, Louisiana State University
TBD
TBD
Posted July 22, 2025
Control and Optimization Seminar Questions or comments?
10:30 am – 11:20 am Zoom (click here to join)
Javad Velni, Clemson University
TBA
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 September 3, 2025
1:00 pm – 4:00 pm Saturday, March 7, 2026 Digital Media Center TheatreScientific Computing Around Louisiana (SCALA) 2026