# Seminars and colloquia

E.g., Nov. 26, 2021

### Otis Chodosh

Stanford
The sine-Gordon equation and the p-widths of a surface

November 30, 2021

Zoom Talk

I will describe recent work with Christos Mantoulidis concerning min-max geodesics related to the p-widths of a surface. A key component of this work relies on recent work of Liu--Wei concerning the sine-Gordon equation, as well as a new bumpy metric theorem for geodesic nets ... Read more
• Differential geometry
• Mathematical Physics
• Partial Differential Equations

### Tom Roby

U Conn.
An action-packed introduction to homomesy

November 30, 2021

Zoom - https://ubc.zoom.us/j/62676242229?pwd=RURtUC9UYXEweVZTMTNGT1EvY1FLZz09

Dynamical algebraic combinatorics explores maps on sets of discrete combinatorial objects with particular attention to their orbit structure. Interesting counting questions immediately arise: How many orbits are there? What are their sizes? What is the period of the map if it' ... Read more
• Discrete mathematics

### Erhard Neher

University of Ottawa

December 1, 2021

We discuss several results, well-known for quadratic forms over fields, in the setting of quadratic forms over arbitrary semilocal rings. Among them are Springer’s odd degree extension theorem and the norm principles of Scharlau and of Knebusch. The talk is based on joint work ... Read more
• Algebra and Algebraic geometry

### Peleg Michaeli

Carnegie Mellon University
Greedy maximal independent sets via local limits

December 1, 2021

The random greedy algorithm for finding a maximal independent set in a graph has been studied extensively in various settings in combinatorics, probability, computer science, and even chemistry. The algorithm builds a maximal independent set by inspecting the graph's vertices ... Read more
• Probability

### Ellen Eischen

University of Oregon
p-adic aspects of L-functions, with a view toward Spin L-functions

December 1, 2021

Online

$p$-adic aspects of $L$-functions, with a view toward Spin $L$-functions \noindent \textbf{Abstract:} The study of $p$-adic properties of values of $L$-functions dates back to Kummer's study of congruences between values of the Riemann zeta function at negative odd integers, ... Read more
• Number Theory

### Han Lu

UBC
Mobius Invariant Equations in Dimension Two

December 7, 2021

PIMS Lounge

Conformally invariant equations in $n\geq3$ have played an important role in the study of $\sigma_k$-Yamabe problem in geometric analysis. In this talk, we will discuss a class of Mobius invariant equations in dimension two and then present a Liouville type theorem for such ... Read more
• Differential geometry
• Mathematical Physics
• Partial Differential Equations

### Michael Bate

University of York
Overgroups of regular unipotent elements in algebraic groups

December 8, 2021

I will talk about a recent paper with Ben Martin and Gerhard Roehrle on subgroups containing regular unipotent elements in reductive algebraic groups. The main result which I will describe is not itself new (it is due to Testerman and Zalesski), but the new proof we came up ... Read more
• Algebra and Algebraic geometry

### Rustum Choksi

McGill University
Math Bio Seminar - Choksi

December 8, 2021

Zoom - contact Katie Faulkner for link

• Mathematical Biology

### Prajeet Bajpai

UBC Vancouver
Effective Methods for Norm-Form Equations

December 8, 2021

Online

Let $\alpha_1,\ldots,\alpha_k$ be linearly independent elements of a number field $K$ of degree $n \ge k$, and let $m$ be an integer. The equation $\mathrm{Norm}_{K/\mathbb{Q}} (x_1\alpha_1 + \cdots + x_k\alpha_k) = m$, to be solved in integers, is called a `norm-form equation ... Read more
• Number Theory

### Olivier Wittenberg

Université Sorbonne Paris Nord
Massey products in the Galois cohomology of number fields

December 15, 2021

(Joint work with Yonatan Harpaz.) Let k be a field and p be a prime. According to a conjecture of Mináč and Tân, Massey products of n>2 classes in H^1(k,Z/pZ) should vanish whenever they are defined. We establish this conjecture when k is a number field, for any n. This ... Read more
• Algebra and Algebraic geometry