# Events - 2019

Wednesday, October 2, 2019 — 3:30 PM EDT

## Analysis Seminar

Carlos Cabrelli, Universidad de Buenos Aires

"Recent Advances in Dynamical Sampling"

Tuesday, October 1, 2019 — 2:00 PM EDT

## Logic Seminar

Matthew Harrison-Trainor, Victoria University of Wellington

"Introcomputability"

Monday, September 30, 2019 — 11:30 AM EDT

## Valuative Tree Seminar

Brett Nasserden, Department of Pure Mathematics, University of Waterloo

"The valuative tree at infinity"

To study the dynamics of a polynomial map on the complex affine plane we must be able to study the behavior of the mapping near the origin and near infinity. The study of the dynamics near a point leads to the notion of the valuative tree at the origin of the affine plane. To study the dynamics near infinity, we introduce a new but analogous object,the valuative tree at infinity, which will be the subject of this lecture.

MC 5403

Friday, September 27, 2019 — 11:00 AM EDT

## PhD Thesis Defence

Sylvie Davies, Department of Pure Mathematics, University of Waterloo

"Algebraic Approaches to State Complexity of Regular Operations"

Thursday, September 26, 2019 — 11:00 AM EDT

## Model Theory Learning Seminar

Wilson Poulter, Department of Pure Mathematics, University of Waterloo

"NIP II"

We finish up section 2.1 and begin section 2.2 of Simon's Guide to NIP theories.

MC 5413

Wednesday, September 25, 2019 — 3:30 PM EDT

## Analysis Seminar

Mizanur Rahaman, Department of Pure Mathematics, University of Waterloo

"Bisynchronous games and factorizable maps"

Tuesday, September 24, 2019 — 2:00 PM EDT

## Computability Learning Seminar

Dino Rossegger, Department of Pure Mathematics, University of Waterloo

"The complexity of Scott sentences of scattered linear orders -- Part II"

Monday, September 23, 2019 — 4:00 PM EDT

## Colloquium

Alex Iosevich, University of Rochester

"Analytic, geometric and combinatorial aspects of the Falconer distance conjecture"

Monday, September 23, 2019 — 2:30 PM EDT

## Valuative Tree Seminar

**Note time and room change**

Ehsaan Hossain, Department of Pure Mathematics, University of Waterloo

"Introduction to the valuative tree"

Thursday, September 19, 2019 — 1:00 PM EDT

Adam Humeniuk, Department of Pure Mathematics, University of Waterloo

"C*-covers of semicrossed products"

Wednesday, September 18, 2019 — 3:30 PM EDT

## Analysis Seminar

Aasaimani Thamizhazhagan, Department of Pure Mathematics, University of Waterloo

"On the structure of invertible elements in Fourier-Stieltjes algebras"

Tuesday, September 17, 2019 — 2:00 PM EDT

## Computability Learning Seminar

Dino Rossegger, Department of Pure Mathematics, University of Waterloo

"The complexity of Scott sentences of scattered linear orders"

Tuesday, September 17, 2019 — 1:30 PM EDT

## Number Theory Seminar

J.C. Saunders, Ben Gurion University of Negev

"Diophantine equations involving the Euler totient function"

We deal with various Diophantine equations involving the Euler totient function. In particular, for $a,b,c,m,n\in\mathbb{N}$ with $m\geq 2$ we study the equations $\varphi(ax^m)=\frac{b\cdot n!}{c}$ and $\varphi\left(\frac{b\cdot n!}{c}\right)=ax^m$ where $\varphi(x)$ is the Euler totient function. We also deal with similar equations involving Lucas sequences of the first kind and second kind, generalising the work of Luca and Stanica.

Thursday, September 12, 2019 — 4:30 PM EDT

Adina Goldberg, Department of Pure Mathematics, University of Waterloo

"This title contains information"

How can we mathematically test the claim made in the title? In this talk, we will learn about Claude Shannon's entropy and determine if it gives us the best measure of informativeness. If you can picture the graph of a logarithm, you are well prepared.

MC 5501

Monday, September 9, 2019 — 4:00 PM EDT

## Colloquium

Shai Ben-David, School of Computer Science, University of Waterloo

"A basic machine learning problem is independent of set theory"

Thursday, August 15, 2019 — 10:00 AM EDT

## Computability Learning Seminar

Michael Deveau, Department of Pure Mathematics, University of Waterloo

"Computability of Walker's Cancellation Theorem"

Monday, August 12, 2019 — 1:00 PM EDT

## Valuative Tree Seminar

Ehsaan Hossain, Department of Pure Mathematics, University of Waterloo

"Fixed point theorem for trees"

Brett and Matt talked about $V_0$ and $V_\infty$, two different subtrees of the Berkovich plane. All of these are rooted trees. I will either talk about potential theory on trees, or the theorem that every tree map admits a fixed point.

MC 5403

Thursday, August 8, 2019 — 10:00 AM EDT

## Computability Learning Seminar

Luke MacLean, Department of Pure Mathematics, University of Waterloo

"Effectively defining formulas in Robinson's Arithmetic"

It was proven by Alfred Tarski that all general recursive functions are definable in Robinson's Arithmetic. I will give his proof of this fact with supplementary information on how to make the process of finding the defining formula effective.

MC 5479

Tuesday, August 6, 2019 — 2:30 PM EDT

## Algebra Seminar

**Please note date change**

Abdullahi Umar, Khalifa University of Science and Technology, Abu Dhabi, UAE

''Some Remarks on Monoids of Contraction Mappings of a Finite Chain"

Tuesday, August 6, 2019 — 9:30 AM EDT

## Geometry Working Seminar

Speaker 1: Spencer Whitehead, Department of Pure Mathematics, University of Waterloo

"Regular polytopes and uniform polytopes"

Friday, August 2, 2019 — 10:30 AM EDT

## PhD Thesis Defense

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

"Rational approximations on smooth rational surfaces"

Thursday, August 1, 2019 — 3:30 PM EDT

## Number Theory Seminar

Arthur Baragar, University of Nevada

“Apollonian packings and Enriques surfaces”

Tuesday, July 30, 2019 — 1:00 PM EDT

## Valuative Trees Learning Seminar

Matthew Satriano, Department of Pure Mathematics, University of Waterloo

“The valuative tree in action”

A sketch of Xie’s proof of Medvedev-Scanlon for Affine 2-space

Tuesday, July 30, 2019 — 9:00 AM EDT

## Geometry Working Seminar

Anton Iliashenko and Spiro Kargiannis, Department of Pure Mathematics University of Waterloo

“First and Second variation of the Volume functional”

Abstract

In this talk we will derive the first and second variational formulas for the volume functional of a submanifold.

“Vector cross products and calibrations: some non-standard inner product space theory”

Monday, July 29, 2019 — 4:00 PM EDT

## Model Theory Seminar

Martin Hils, Universitat Munster

“Equivariant definable deformation retractions in non-archimedean geometry” (joint work with Ehud Hrushovski and Pierre Simon)”

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