Seminars and Colloquia by Series

Universality limits for orthogonal polynomials

Series
Math Physics Seminar
Time
Friday, January 23, 2026 - 11:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Milivoje LukicEmory University

The local spacing of zeros of orthogonal polynomials is studied using scaling limits of Christoffel--Darboux kernels. Different limit kernels are associated with different universality classes, e.g. sine kernel with bulk universality and locally asymptotically uniform zero spacing. In recent years, new results have been obtained by using the de Branges theory of canonical systems. This includes necessary and sufficient conditions for a family of scaling limits corresponding to homogeneous de Branges spaces; this family includes bulk universality, hard edge universality, jump discontinuities in the weight, and other notable universality classes. It also includes local behaviors beyond scaling limits. The talk is based on joint works with Benjamin Eichinger, Brian Simanek, Harald Woracek, Peter Yuditskii.

The Uzawa Method: Historical Perspectives, Current Advances, and Future Directions

Series
Applied and Computational Mathematics Seminar
Time
Friday, January 23, 2026 - 11:00 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Professor Xiaoming YuanThe University of Hong Kong

Abstract:
This talk explores the Uzawa method, tracing its development from early applications in partial differential equations (PDEs) to modern advancements in optimization, image processing, and scientific computing. We will examine recent refinements for developing GPU-adaptive solvers for huge-scale linear programming and its extension to semidefinite programming arising in quantum information science. The discussion will also highlight the method's integration with deep learning and unrolling techniques for optimal control problems of PDEs, as well as its applications in industry.

 

Bio:

Xiaoming Yuan is a Professor in the Department of Mathematics at The University of Hong Kong. His research spans optimization, optimal control, scientific machine computing, and artificial intelligence. He is well recognized for his fundamental contributions to first-order optimization algorithms, including the Alternating Direction Method of Multipliers (ADMM), primal-dual methods, and proximal point algorithms. He also collaborates extensively with the AI and cloud computing industries. He led the development of the first automatic bandwidth allocation system for the cloud computing sector. His team was honored as a Franz Edelman Award Finalist in 2023.

Similarities and Differences between the Longest Common and Longest Common and Increasing Subsequences in Random Words

Series
Stochastics Seminar
Time
Thursday, January 22, 2026 - 15:30 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Christian HoudréGeorgia Institute of Technology

Let $LC_n$ be the length of the longest common subsequences of two independent random words whose letters are taken  in a finite alphabet and when the alphabet is totally ordered and let $LCI_n$ be the length of the longest common and increasing subsequences of the words.   Results on the asymptotic means, variances and limiting laws of these well-known random objects will be described and compared.

Computer Algebra club/seminar

Series
Additional Talks and Lectures
Time
Wednesday, January 21, 2026 - 13:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Anton LeykinGeorgia Tech

Let us discuss how to use generative AI to help with math and coding.

My presentation features two scenarios:

Coding in LaTeX. Suppose you have a raw draft of what potentially could be a math paper. We will consider and apply simple AI tools that may help realizing the potential.

Coding in CAS. Suppose you have a raw idea for a package in a Computer Algebra System; your raw idea may be limited to a rough description of the input/output of a method you would like to implement. How far can an AI assistant take you? Can it autonomously code a working software package?   

 

Some upper and lower bounds on the variance of functions of independent random variables

Series
Probability Working Seminar
Time
Tuesday, January 20, 2026 - 15:30 for 1.5 hours (actually 80 minutes)
Location
Skiles 006
Speaker
Christian HoudréGeorgia Tech

Please Note: Second of several talks.

I'll present various methods, some old, some new,  leading to estimates on the variance of $f(X_1, X_2, \dots, X_n)$ where  

$X_1, X_2, \dots, X_n$ are independent random variables.  These methods will be illustrated with various examples.

Mass inflation for spherically symmetric charged black holes

Series
PDE Seminar
Time
Tuesday, January 20, 2026 - 15:30 for 1 hour (actually 50 minutes)
Location
Skiles 254
Speaker
Onyx Gautam Princeton University

The Reissner–Nordström spacetime models a spherically symmetric and time-independent charged black hole in general relativity. The Cauchy horizon in the interior of such a black hole is subject to an infinite blueshift instability. In 1989, Poisson and Israel discovered a nonlinear manifestation of this instability in the spherically symmetric setting called "mass inflation," where the Hawking mass becomes identically infinite at the Cauchy horizon. 

We complete the first proof of mass inflation for a wave-type matter model, namely the spherically symmetric Einstein–Maxwell–scalar field system. This result follows from a large-data decay result for the scalar field in the black hole exterior combined with works of Dafermos, Luk–Oh, and Luk–Oh–Shlapentokh-Rothman.

Double exponential mixing in analytic dynamics

Series
CDSNS Colloquium
Time
Friday, January 16, 2026 - 15:00 for 1 hour (actually 50 minutes)
Location
Skiles 314
Speaker
Ekaterina ShchetkaUniversity of Michigan

In dynamics, the speed of mixing depends on the dynamical features of the map and the regularity of the observables. Notably, two classical linear models—the Bernoulli doubling map and the CAT map—exhibit double exponential mixing for analytic observables. Are ergodic linear maps the only ones with this property? In dimension one, we provide a full classification for maps from the space of volume-preserving finite Blaschke products acting on the circle (as well as for free semigroup actions generated by a finite collection of such maps). In higher dimensions, we identify a necessary condition for double exponential mixing and present several families of examples and non-examples. Key ideas of the proof involve the Koopman precomposition operator on spaces of hyperfunctions (elements of the dual space of analytic functions), which turns out to be non-self-adjoint, compact, and quasi-nilpotent, with spectrum reduced to zero.

 

https://gatech.zoom.us/j/97077908574?pwd=bnP9YWZwqKsU5YrgFZR40asqub0GOR.1

Meeting ID: 970 7790 8574

Passcode: 604975

How trustworthy AI enables a paradigm shift in classical statistics for particle physics

Series
Stochastics Seminar
Time
Thursday, January 15, 2026 - 15:30 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Aishik GhoshGeorgia Tech

Particle physics research relies on making statistical statements about Nature. The field is one of the last bastions of classical statistics and certainly among its most rigorous users, relying on a worldwide computing grid to process zettabyte-scale data. Recent AI-enabled developments have reinvigorated research in classical statistics, particularly by removing the need for asymptotic approximations in many calculations.

 

In this talk, I will discuss how AI has allowed us to question core assumptions in our statistical inference techniques. Neural networks enable high-dimensional statistical inference, avoiding aggressive data reduction or the use of unnecessary assumptions. However, they also introduce new sources of systematic uncertainty that require novel uncertainty quantification tools. AI further enables more robust statistical inference by accelerating Neyman inversion and confidence-interval calibration. These advances allow the design of new test statistics that leverage Bayesian mathematical tools while still guaranteeing frequentist coverage, an approach that was previously considered computationally infeasible. These new techniques raise questions about practical methods for handling nuisance parameters, the definition of point estimators, and the computationally efficient implementation of mathematical solutions. If time permits, I will also introduce the emerging challenge of non-nestable hypothesis testing in particle physics.

 

My group is among the teams leading this revitalization of classical statistical research in particle physics, and I look forward to connecting with students and senior colleagues at Georgia Tech who are interested in contributing to this emerging field.

 

Bio: Aishik Ghosh is an assistant professor in the School of Physics at Georgia Tech with a focus on developing AI methods to accelerate fundamental physics and astrophysics. His group works on theoretical physics, statistical methods, and experiment design. For robust scientific applications, Dr. Ghosh focuses on uncertainty quantification, interpretability, and verifiability of AI algorithms, targeting publications in physics journals and ML conferences.

Maximization of recurrent sequences, Schur positivity, and derivative bounds in Lagrange interpolation

Series
Analysis Seminar
Time
Wednesday, January 14, 2026 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Dmitrii OstrovskiiGeorgia Institute of Technology

Consider the following extremal problem: maximize the amplitude |X_T|, at time T, of a linear recurrent sequence X_1, X_2,... of order N < T, under natural constraints: (I) the initials are uniformly bounded; (II) the characteristic polynomial is R-stable, i.e., its roots are in the origin-centered disc of radius R. While the maximum at time T = N essentially follows from the classical Gautschi bound (1960), the general case T > N turns out to be way more challenging to handle. We find that for any triple (N,R,T), the amplitude is maximized when the roots coincide and have modulus R, and the initials are chosen to align the phases of fundamental solutions. This result is striking for two reasons. First, the same configuration of roots and initials is uniformly optimal for all T, i.e. the whole envelope is maximized at once. Second, we are not aware of any purely analytical proof: ours uses tools from algebraic combinatorics, namely Schur polynomials indexed by hook partitions. 

In the talk, I will sketch the proof of this result, making it as self-sufficient as possible under the circumstances. If time permits, we will discuss a related conjecture on the optimal error bounds in complex Lagrange interpolation.

The talk is based on the work https://arxiv.org/abs/2508.13554.

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