# Events - August 2019

Thursday, August 15, 2019 — 2:30 PM EDT

## Algebraic Graph Theory Seminar - Chris Godsil

Title: Upsetting Matrices

 Speaker: Chris Godsil Affiliation: University of Waterloo Room: MC 5479

Abstract:

If $A$ and $P$ are $n\times n$ matrices and the entries of $B$ are small, we may view $A+B$ as a perturbation of $A$, and expect that the spectral properties of $A+B$ should be related to those of $A$.
Thursday, August 8, 2019 — 2:30 PM EDT

## Algebraic Graph Theory - Soffia Arnadottir

Title: Continuous Quantum Walks

 Speaker: Soffia Arnadottir Affiliation: University of Waterloo Room: MC 5479

Abstract:

Continuous quantum walks are of considerable interest in quantum physics and quantum computing.

Tuesday, August 6, 2019 — 3:30 PM EDT

## Algebraic Combinatorics Seminar - Adrian Tanasa

Title: Feynman graphs, ribbon graphs and tensor graphs

 Speaker: Adrian Tanasa Affiliation: Université de Bordeaux Room: MC 5479

Abstract:

In this talk I will define the so-called Feynman graphs, which are a particular class of graphs appearing in quantum field theory.

Friday, August 2, 2019 — 3:30 PM EDT

## Tutte Colloquium - Jamie Sikora

Title: Optimization and Cryptography in Generalized Physical Theories

 Speaker: Jamie Sikora Affiliation: Perimeter Institute Room: MC 5501

Abstract:

In this talk, I will discuss three important cryptographic tasks in the quantum and post-quantum world. I will discuss the impossibility of bit-commitment and coin-flipping, and also the possibility of physically unforgeable money in the framework of Generalized Physical Theories (GPTs).

Friday, August 2, 2019 — 1:00 PM EDT

## Combinatorial Optimization Reading Group - Matthew Louis Gerstbrein

Title: Stable marraige with general preferences

 Speaker: Matthew Louis Gerstbrein Affiliation: University of Waterloo Room: MC 5479

Abstract:

This week, we discuss a generalization of the standard stable marriage problem, in which one side has a complete, totally ordered, strict preference list while the other has preferences given in terms of arbitrary binary relations.

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

## Algebraic Combinatorics Seminar - Clair Dai

Title: Counting subdivergence-free gluing of trees

 Speaker: Clair Dai Affiliation: University of Waterloo Room: MC 5417

Abstract:

If we take two rooted trees with the same number of leaves and form a graph by gluing the leaves of one tree to the other, then we say the graph is subdivergence-free if no 2-edge cut have been generated.

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

## Algebraic Combinatorics Seminar - Lily Wang

Title: The combinatorics of nearest and furthest values

 Speaker: Lily Wang Affiliation: University of Waterloo Room: MC 5417

Abstract:

A classical problem asks us to find, for each element $A[i]$ of an array of integers, the position of the nearest smallest element.

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

## Algebraic Combinatorics Seminar - Yuval Ohapkin

Title: Bijections among symmetric tableaux via folding and mixed insertion

 Speaker: Yuval Ohapkin Affiliation: University of Waterloo Room: MC 5417

Abstract:

A standard Young tableau with entries $-M < \cdots -1 < 1 < \cdots < M$ can be "folded" by performing certain conversions and rectifications in sequence.

Thursday, August 1, 2019 — 2:30 PM EDT

## Algebraic Graph Theory - Chris Godsil

Title: Non-Commutative Algebras and Graphs

 Speaker: Chris Godsil Affiliation: University of Waterloo Room: MC 5479

Abstract:

I will discuss some of the non-commutative algebras that arise naturally in graph theory.

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