# Past Events

E.g., Feb 5, 2023

### Sinho Chewi

Towards a theory of complexity of sampling, inspired by optimization

February 3, 2023

Sampling is a fundamental and widespread algorithmic primitive that lies at the heart of Bayesian inference and scientific computing, among other disciplines. Recent years have seen a flood of works aimed at laying down the theoretical underpinnings of sampling, in analogy to the fruitful and... Read more

• Mathematics of Information

### Sinho Chewi

Two applications of reversed SDEs to sampling

February 2, 2023

I will discuss two recent applications of reversed diffusions to sampling: the proximal sampler and score-based generative models (SGMs). First, the proximal sampler, which is the sampling analogue of the proximal point method from optimization, is an attractive alternative to the well-studied... Read more

• Mathematics of Information

### Santanil Jana

UBC
The Cohomology of Unordered Flag Manifolds

February 1, 2023

Room 204

The space U(n)/N(n), where N(n) is the normalizer of the maximal torus in U(n), arises naturally in many areas of mathematics and can be identified with the unordered flag manifolds. In this talk, we will introduce the concept of the n-fold extended symmetric power of a space X, and describe its... Read more

• Topology

### János Engländer

Tree builder random walks

February 1, 2023

We investigate a self-interacting random walk, in a dynamically evolving environment, which is a random tree built by the walker itself, as it walks around.

At time $n=1,2,\dots$, right before stepping, the walker adds a random number (possibly zero) $Z_n$ of leaves to its current... Read more

• Probability

### Jonah Brooks Hall

UBC Math
Math bio seminar - Hall

February 1, 2023

ESB 4133

• Mathematical Biology

### Peter McNamara

Bucknell University
When do quasisymmetric functions know that trees are different?

January 31, 2023

Zoom

A famous conjecture of Stanley states that his chromatic symmetric function distinguishes trees. As a quasisymmetric analogue, we conjecture that the chromatic quasisymmetric function of Shareshian and Wachs and of Ellzey distinguishes directed trees. This latter conjecture would be implied by... Read more

• Discrete mathematics

### Ahmet Alacaoglu

Stochastic Variance Reduction for Min-Max Optimization and Variational Inequalities

January 31, 2023

Stochastic variance reduction techniques have been influential for developing algorithms for minimization problems in the last decade whereas their use in more general problem templates has been limited. This talk will present a first order algorithm with variance reduction to solve convex-... Read more

• Mathematics of Information

### Elliot Cheung

UBC
A discretization of a derived moduli space arising from gauge theory

January 30, 2023

MATH 126

One could say that an ulterior motive for this talk is to understand, through an example, how to construct derived moduli spaces out of L-infinity algebras (which are homotopical generalizations of Lie algebras). L-infinity algebras produce derived moduli spaces or stacks, and we will see how... Read more

• Algebra and Algebraic geometry

### Ahmet Alacaoglu

Benefits of Randomization on First Order Algorithms for Min-Max Optimization

January 30, 2023

Modern data science applications require solving high dimensional optimization problems with large number of data points. Min-max optimization provides a unified framework for many problems in this context ranging from empirical risk minimization and distributionally robust optimization in... Read more

• Mathematics of Information

### Frederic Koehler

Towards the Statistically Principled Design of ML Algorithms

January 27, 2023

What are the optimal algorithms for learning from data? Have we found them already, or are better ones out there to be discovered? Making these questions precise, and answering them, requires taking on the mathematically deep interplay between statistical and computational constraints. It also... Read more

• Mathematics of Information