# Events

Monday, October 23, 2017 — 4:00 PM EDT

## Pure Mathematics Colloquium

Damien Roy, University of Ottawa

"Diophantine curiosities"

Friday, October 20, 2017 — 3:30 PM EDT

## Analysis Seminar

Yiu-Tung Poon, Iowa State University

"(p,q) Matricial Range and Quantum Information Science"

Friday, October 20, 2017 — 2:30 PM EDT

## Geometry and Topology Seminar

Esther Cabezas-Rivas, Universität Frankfurt

"Ricci flow beyond non-negative curvature conditions"

We generalize most of the known Ricci flow invariant non-negative curvature conditions to less restrictive negative bounds that remain sufficiently controlled for a short time.

Thursday, October 19, 2017 — 3:30 PM EDT

## Universal Algebra Seminar

Justin Laverdure, Department of Pure Mathematics, University of Waterloo

"A finite pointed group with no finite basis, Part 1"

We'll go over a construction of Roger Bryant, by building a finite pointed group (P,p) with no finite basis for its laws, as far as we can go. We'll recap basic equational theory stuff, then wade knee-deep into semidirect products and counting arguments.

MC 5413

Thursday, October 19, 2017 — 2:30 PM EDT

## Analysis Seminar

Adam Dor On, Technion

"Cuntz-Nica-Pimsner algebras over $\mathbb{N}^d$"

An effective model for encoding multivariable dynamical systems via C*-algebras is given by Toeplitz-Nica-Pimsner algebras introduced by Fowler. In the work of Carlsen, Larsen, Sims and Vitadello, the right notion of a "boundary quotient" Cuntz-Nica-Pimsner algebra is established, but the precise relations between minimal generators are sometimes very difficult to ascertain.

Thursday, October 19, 2017 — 1:30 PM EDT

## Number Theory Seminar

John Friedlander, University of Toronto

"Exceptional characters and their consequences"

We review some history about the possible existence of certain Dirichlet characters which might possess a zero very close to the line $Re s = 1$ and the remarkably strong consequences which could be derived under the assumption of their existence.

MC 5501

Wednesday, October 18, 2017 — 3:30 PM EDT

## Branching Processes Learning Seminar

Sascha Troscheit, Department of Pure Mathematics, University of Waterloo

"Branching Processes, Martingales, Kingman’s Subadditive Ergodic Theorem, and some applications, Part III: The probability of deviating from the mean behaviour"

Tuesday, October 17, 2017 — 4:00 PM EDT

## Model Theory Seminar

Levon Haykazyan, Department of Pure Mathematics, University of Waterloo

"Introduction to Positive Logic"

Tuesday, October 17, 2017 — 1:30 PM EDT

## Algebraic Geometry Learning Seminar

Diana Castaneda Santos, Department of Pure Mathematics, University of Waterloo

"Review (Episode 3)"

We will continue our review of schemes. We will mention some examples of schemes that are not affine schemes. We will review the proj construction, and more topological properties of schemes. If time permits we'll define morphisms of schemes.

MC 5413

Monday, October 16, 2017 — 4:00 PM EDT

## Pure Mathematics Colloquium

Karen Yeats, Department of Combinatorics & Optimization, University of Waterloo

"Chord diagram expansions in quantum field theory"

Over the last few years we have been able to re-expand certain series in perturbative quantum field theory using chord diagrams.  These new expansions have nice mathematical structure.  I will give an overview on them and how they can be useful.

MC 5501

Thursday, October 12, 2017 — 3:30 PM EDT

## Universal Algebra Seminar

Andrei Krokhin, Durham University

"The complexity of valued constraint satisfaction problems"

Wednesday, October 11, 2017 — 3:30 PM EDT

## Algebra Seminar

Rekha Biswal, Université Laval

"Demazure flags, Chebyshev polynomials and mock theta functions"

Wednesday, October 11, 2017 — 3:30 PM EDT

## Branching Processes Learning Seminar

Sascha Troscheit, Department of Pure Mathematics, University of Waterloo

"Branching Processes, Martingales, Kingman’s Subadditive Ergodic Theorem, and some applications, Part II: The almost sure number of descendants and finer information, such as expected deviations from the average behaviour and `immigration'"

Friday, October 6, 2017 — 3:30 PM EDT

## Analysis Seminar

Ping Zhong, Department of Pure Mathematics, University of Waterloo

"Estimates for compression norms and additivity violation in quantum information"

Friday, October 6, 2017 — 2:30 PM EDT

## Geometry and Topology Seminar

Ajneet Dhillon, University of Western Ontario

"Tamagawa numbers and connected components of stacks"

Let X be a smooth projective curve over a finite field and $G$ a semisimple algebraic group over its function field. Let $\mathcal{G}$ be a smooth group scheme over X with generic fiber $G$. The Tamagawa number of $G$ is an arithmetic invariant obtained from a Haar measure on the adelic points of $G$. A conjecture of Harder relates this number to the number of components of the moduli stack of $\mathcal{G}$-bundles.

Thursday, October 5, 2017 — 3:30 PM EDT

## Universal Algebra Seminar

Ross Willard, Department of Pure Mathematics, University of Waterloo

"An introduction to finite basis problems"

To get us started this term, I will describe some known instances of the finite basis problem in universal algebra, and one unknown instance that is currently bugging me: “Murskii + L'vov.”  This will be an elementary lecture, intended as a warm-up for Justin’s lectures later this month.

MC 5413

Thursday, October 5, 2017 — 1:30 PM EDT

## Number Theory Seminar

Lucile Devin, University of Ottawa

"Generalizations of Chebyshev's bias"

Wednesday, October 4, 2017 — 4:30 PM EDT

## Joint Graduate Student Colloquium

Sam Kim, Department of Pure Mathematics, University of Waterloo

"I'll prove the Fundamental Theorem of Algebra"

Gauss proved that complex polynomials always admit a root. I'll explain how he came to that conclusion and present a proof that rigorizes his argument in a nice way. You will only need to know a little vector calculus and the intermediate value theorem. If we have time, I'll show you why a flat triangle has angles that add up to π and why a triangle on a sphere doesn't.

MC 5501

Wednesday, October 4, 2017 — 3:30 PM EDT

## Branching Processes Learning Seminar

Sascha Troscheit, Department of Pure Mathematics, University of Waterloo

"Branching Processes, Martingales, Kingman’s Subadditive Ergodic Theorem, and some applications"

Tuesday, October 3, 2017 — 4:00 PM EDT

## Model Theory Seminar

Peter Sinclair, McMaster University

"Dp-finite fields"

Tuesday, October 3, 2017 — 1:30 PM EDT

## Algebraic Geometry Learning Seminar

Patrick Naylor, Department of Pure Mathematics, University of Waterloo

"The Review Continues"

We'll continue our review from last week. This week, we're actually  defining a scheme, as well as giving a quick review of some of the associated topological properties.

MC 5413

Monday, October 2, 2017 — 4:00 PM EDT

## Pure Mathematics Colloquium

**CANCELLED**​

Ragnar-Olaf Buchweitz,  University of Toronto

"The McKay Correspondence Then and Now"

Friday, September 29, 2017 — 3:30 PM EDT

## Analysis Seminar

Eli Shamovich, Pure Mathematics, University of Waterloo

"Free Function Theory on the Noncommutative Ball"

Friday, September 29, 2017 — 2:30 AM EDT

## Geometry and Topology Seminar

Dhruv Ranganathan
MIT

"Moduli of Elliptic Curves in Toric Varieties and Tropical Geometry"

Thursday, September 28, 2017 — 1:30 PM EDT

## Number Theory Seminar

Fan Ge, Pure Mathematics, University of Waterloo

"The number of zeros of $\zeta'(s)$

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