Calendar

Posted November 22, 2025
Last modified January 6, 2026

Control and Optimization Seminar Questions or comments?

Henk van Waarde, University of Groningen IEEE L-CSS Outstanding Paper and SIAM SIAG/CST Prize Awardee
Data-Driven Stabilization using Prior Knowledge on Stabilizability and Controllability

Direct approaches to data-driven control design map raw data directly into control policies, thereby avoiding the intermediate step of system identification. Such direct methods are beneficial in situations where system modelling is computationally expensive or even impossible due to a lack of rich data. We begin the talk by reviewing existing methods for direct data-driven stabilization. Thereafter, we discuss the inclusion of prior knowledge that, in conjunction with the data, can be used to improve the sample efficiency of data-driven methods. In particular, we study prior knowledge of stabilizability and controllability of the underlying system. In the case of controllability, we prove that the conditions on the data required for stabilization are equivalent to those without the inclusion of prior knowledge. However, in the case of stabilizability as prior knowledge, we show that the conditions on the data are, in general, weaker. We close the talk by discussing experiment design methods. These methods construct suitable inputs for the unknown system, in such a way that the resulting data contain enough information for data-driven stabilization (taking into account the prior knowledge).

Posted January 26, 2026
Last modified January 27, 2026

Combinatorics Seminar Questions or comments?

Xiaonan Liu, Vanderbilt University
Counting $k$-cycles in $5$-connected planar triangulations

We show that every $n$-vertex $5$-connected planar triangulation has at most $9n-50$ many cycles of length $5$ for all $n\ge 20$ and this upper bound is tight. We also show that for every $k\geq 6$, there exists some constant $C(k)$ such that for sufficiently large $n$, every $n$-vertex $5$-connected planar graph has at most $C(k) \cdot n^{\lfloor k/3 \rfloor}$ many cycles of length $k$. This upper bound is asymptotically tight for all $k\geq 6$. This is joint work with Gyaneshwar Agrahari and Zhiyu Wang.

Posted January 16, 2026

Algebra and Number Theory Seminar Questions or comments?

Koustav Mondal, Louisiana State University
TBA

Event contact: Gene Kopp

Posted January 22, 2026

Informal Analysis Seminar Questions or comments?

Hari Narayanan, Louisiana State University
Crash Course on Schrödinger Operators (Part 1)

An expository talk in spectral theory.

Posted January 28, 2026

Geometry and Topology Seminar Seminar website

Konrad Wrobel, University of Texas at Austin
Measure equivalence classification of Baumslag-Solitar groups

We complete the classification of Baumslag-Solitar groups up to measure equivalence by showing all Baumslag-Solitar groups with nonunimodular Bass-Serre tree are measure equivalent (i.e., BS(r,s) with r between 1 and s). The proof makes critical use of combinatorial descriptive set theory tools in the measure class preserving setting and passes through the world of measure equivalence of nonunimodular locally compact groups. In particular, as an intermediate step we obtain measure equivalence couplings between all groups of the form Aut(T_{r,s}) for r between 1 and s where T_{r,s} is the directed tree with r incoming edges and s outgoing edges at each vertex. This is joint work with Damien Gaboriau, Antoine Poulin, Anush Tserunyan, and Robin Tucker-Drob.

Posted January 15, 2026

Informal Geometry and Topology Seminar Questions or comments?

Matthew Lemoine, Louisiana State University
TBD

TBD

Posted December 29, 2025

Colloquium Questions or comments?

R. Tyrrell Rockafellar, University of Washington
TBA

Posted December 31, 2025

Control and Optimization Seminar Questions or comments?

R. Tyrrell Rockafellar, University of Washington
TBA