Events - May 2023

Ada Chan, York University

"Complex Hadamard matrices and association schemes, Part 1"

Complex Hadamard matrices and spin models are special cases of type-II matrices. In the 1980s, Vaughan Jones used spin models to construct link invariants and representations of braid groups. The term type II was coined after the second Reidemeister move of link diagrams. In 1990s, Jaeger and Nomura discovered the surprising connection of spin models and association schemes.

David Chodounsky, Institute of Mathematics of the Czech Academy of Sciences

"Countable chromatic number of definable graphs via games"

We define games which characterize countable coloring numbers of analytic graphs on Polish spaces. These games can provide simple verification of the countable chromatic number of certain graphs. (Eg. the rational distance graph on the Euclidean plane.) Joint work with Jindrich Zapletal.

MC 5403

Dongshu Dai, Department of Pure Mathematics, University of Waterloo

"The global loop space"

We will continue with section 3 of Kapranov and Vasserot's paper.

MC 5403

J.C. Saunders, Middle Tennessee State University

"Primes and composites in the determinant Hosoya triangle"

Francisco Villacis, Department of Pure Mathematics, University of Waterloo

"An Introduction to Schemes"

The goal of this talk is to present an overview of Section II.2 of Hartshorne. In particular, I will introduce our main objects of study for this seminar: schemes. I will define what these objects are and study some examples of schemes. If time permits, the second half of the seminar will be devoted to solving some problems from this section of Hartshorne.

MC 5403

Sean Monahan, Department of Pure Mathematics, University of Waterloo

"Coloured fantastacks"

Ben Webster, Department of Pure Mathematics, University of Waterloo

"Vertex algebras, arcs and loops, part 2"

I'll continue with vertex algebras, with an eye to how they arise in algebraic geometry through arc and loop spaces.  

MC 5403

Hanming Liu, Department of Pure Mathematics, University of Waterloo

"Living inside 3-manifolds"

Day to day life gives us a pretty good idea of what it is like living inside 3-dimensional Euclidean space. But what about other 3-manifolds? It turns out that thinking about this question leads to a way of visualizing 3-manifolds without having to visualize 4 or 5-dimensional Euclidean spaces, and to a classification of closed orientable 3-manifolds.

MC 5417

Lorenzo Fatibene, University of Torino

"Spin frames vs spin structures: A framework for Dirac fields in interaction with gravity"

Nick Priebe, University of Waterloo

"Introduction to Hadamard matrices and their quantum symmetries"

Continuing last Thursday's talk, we will introduce the Banica-Nicoara quantum symmetry groups of Hadamard matrices. These provide some interesting quantum groups, and in some sense capture some symmetries associated with the matrix.

MC 5403

Thomas Bray, Department of Pure Mathematics, University of Waterloo

"Boundaries and C*-simplicity of (discrete) groups 2"

I will continue to discuss the contents of the paper “Boundaries of reduced C*-algebras of discrete groups" by Kalantar and Kennedy.

MC 5479

Talk #1

Jérémy Champagne, Department of Pure Mathematics, University of Waterloo

"Diophantine approximation by linear forms with angular restrictions"