Events

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

Francisco Villacis, Department of Pure Mathematics, University of Waterloo

"An Introduction to GIT Quotients"

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.

Rahim Moosa, Department of Pure Mathematics, University of Waterloo

"Restricted Zilber Trichotomy"

We will be reading Ben Castle’s paper.

MC 4060

Ada Chan, York University

"Complex Hadamard matrices and association schemes, Part 2"

This will be a continuation of Wednesday's lecture.  We will discuss the properties of the association schemes of Hadamard graphs and their associated spin models.

MC 5403

Rachael Alvir, Department of Pure Mathematics, University of Waterloo

"Reverse Math II"

In this talk, we will give a preliminary introduction to reverse mathematics. We will be working from a recent book by Damir Dzhafarov and Carl Mummert.

MC 5403

Talk #1: Kareem Alfarra

"On integers n coprime to f(n)"

In a previous discussion, we saw that the set of integers n such that gcd(n, ⌊αn⌋) = 1 for an irrational α has density 6/π². In the same spirit, we investigate the following set of integers n such that gcd(n, f(n)) = 1 where f (1), f (2), . . . is a non-decreasing sequence of positive integers that slowly tends to infinity. Then we see once again that the density of this set is 6/π².

Talk #2: Yash Totani

Talk #1 (1:00 - 2:30pm): Xuemiao Chen, University of Waterloo

"Boundary value problems for G2 holonomy equation and mapping problems for 3 forms on 5-d manifolds"

Michael Brannan and Nick Priebe, Department of Pure Mathematics, University of Waterloo

"Quantum symmetries of Hadamard Matrices, Revisited (Part 1)"

In this two-part talk, we will revisit quantum automorphisms of Hadamard matrices, following the preprint of D. Gromada (arxiv:2210.02047v3).  We will compare this with the original definition of Banica-Nicoara introduced in the seminar a few weeks ago, and connect it to the quantum automorphism groups of Hadamard graphs.

MC 5403

**THIS TALK HAS BEEN RESCHEDULED UNTIL NEXT WEEK**

Rahim Moosa, Department of Pure Mathematics, University of Waterloo

"Restricted Zilber Trichotomy"

We will be reading Ben Castle's paper.

MC 4060