# Events - 2022

Monday, June 6, 2022 — 10:00 AM to Tuesday, June 7, 2022 — 5:00 PM EDT

## Algebraic Combinatorics Virtual Expedition (AlCoVE)

AlCoVE aims to bring together researchers interested in algebraic combinatorics from around the world. Each talk will be 30 minutes and between talks, there will be casual social activities for spending time with your friends and making new friends.

To access the Zoom links, you must first register for the conference.

#### Registration

To register, click here.

Friday, May 27, 2022 — 3:30 PM EDT

## Tutte Colloquium - Ian Goulden & David Jackson

Title: Early Work

Abstract:

I will talk briefly and informally about my work in the last century.

Title: At It and In It

Abstract:

I have selected seven Research Themes to talk about very briefly and informally.  They are reflections upon key moments and surprising revelations over the past forty years.

Thursday, May 26, 2022 — 11:30 AM EDT

## Cryptography Reading Group - Dinesh Valluri

Title: Faster Algorithms for Isogeny Problems using Torsion Point Images.

 Speaker: Dinesh Valluri Affiliation: University of Waterloo Attend: Contact Jesse Elliott

Abstract:

In this talk, we will discuss cryptanalysis of some SIDH-type protocols due to Christophe Petit: https://eprint.iacr.org/2017/571.pdf. While finding isogenies between supersingular elliptic curves remains computationally hard to solve, knowledge of images of specific torsion points by the unknown isogeny helps build faster attacks.

Tuesday, May 24, 2022 — 3:00 PM EDT

## Graphs and Matroids Seminar - Peter Nelson

Title: On Donuts and Quasigraphic matroids

 Speaker: Peter Nelson Affiliation: University of Waterloo Room: MC 5417

Abstract:

Quasigraphic matroids are graph-like objects that give a common generalization of lift and frame matroids. Donuts are edible topological surfaces. I will talk about a surprising link between these two types of object, assuming no prior knowledge of quasigraphic matroids or donuts.

Tuesday, May 24, 2022 — 9:00 AM to Friday, May 27, 2022 — 4:30 PM EDT

## Combinatorial and Algebraic Enumeration

A celebration of Goulden and Jackson's combined 90 years of insight and inspiration that have shaped the fields of algebraic and combinatorial enumeration.

#### Registration

Friday, May 20, 2022 — 3:30 PM EDT

## Tutte Colloquium - Frank de Meijer

Title: The Chvátal-Gomory procedure for integer SDPs with applications in combinatorial optimization

Abstract:

Semidefinite programs under the presence of integrality constraints are known as integer semidefinite programs (ISDPs). Since the combination of integrality and positive semidefiniteness leads to matrices that are highly structured, ISDPs have applications in several fields, including architecture and combinatorial optimization.

Thursday, May 19, 2022 — 1:00 PM EDT

## Algebraic Combinatorics Seminar - Victor Wang

Title: P-partition power sums

 Speaker: Victor Wang Affiliation: University of British Columbia Room/Zoom: MC5479 or for Zoom link contact Logan Crew or Olya Mandelshtam

Abstract:

The Hopf algebra of symmetric functions is spanned by several important bases, including by power sum symmetric functions, which encode the class values of the characters of the symmetric group under the Frobenius characteristic map.

Tuesday, May 17, 2022 — 3:00 PM EDT

## Graphs and Matroids Seminar - Jorn van der Pol

Title: Almost every matroid has a rank-3 wheel or rank-3 whirl as minor

 Speaker: Jorn van der Pol Affiliation: University of Waterloo Room: MC 5417

Abstract:

Many conjectures – but few results – exist for the statistical properties of large "random" matroids. For example, the question which matroids appear as a minor of almost every matroid has been settled for only a few matroids.

Friday, May 13, 2022 — 3:30 PM EDT

## Tutte Colloquium - Rafael Oliveira

Title: Radical Sylvester-Gallai theorem for cubics - and beyond

Abstract:

In 1893, Sylvester asked a basic question in combinatorial geometry: given a finite set of distinct points $v_1, \ldots, v_m \in \R^N$ such that the line defined by any pair of distinct points $v_i, v_j$ contains a third point $v_k$ in the set, must all points in the set be collinear?

Friday, May 13, 2022 — 8:30 AM to Saturday, May 14, 2022 — 5:00 PM EDT

## 26th Ontario Combinatorics Workshop

The Ontario Combinatorics Workshop is a meeting for researchers working in combinatorics from Ontario and surrounding areas to gather and share their latest research developments. The objective of this meeting is to have an atmosphere conducive to research discussion and collaboration. The setting of the meeting is informal to provide a friendly environment for students and post-doctoral fellows to present their results, to exchange ideas, and to gain exposure to various topics in combinatorics. It is also a place where students and faculties meet, which may foster future collaborations.

#### Registration

To register, click here.

Thursday, May 12, 2022 — 1:00 PM EDT

## Algebraic Combinatorics Seminar - Andrew Gitlin

Title:  A vertex model for LLT polynomials and k-tilings of the Aztec diamond

 Speaker: Andrew Gitlin Affiliation: UC Berkeley Room/Zoom: MC5479 or for Zoom link contact Logan Crew or Olya Mandelshtam

Abstract:

We describe a Yang-Baxter integrable colored vertex model, from which we construct a class of partition functions that equal the LLT polynomials of Lascoux, Leclerc, and Thibon. Using the vertex model formalism, we can prove many properties of these polynomials.

Thursday, May 12, 2022 — 11:30 AM EDT

## Cryptography Reading Group - Ted Eaton

Title: Recent developments in key-blinding

 Speaker: Ted Eaton Affiliation: University of Waterloo Attend: Contact Jesse Elliott

Abstract:

Key-blinding is an extension to signature schemes for use in some anonymity networks. It allows identity public keys to be deterministically transformed into a blinded public key that conceal the original. Signatures can still be issued and verified with respect to the blinded key. This is useful when intermediaries in anonymity networks are not entirely trusted, but still need to verify signatures with respect to some public key.

Tuesday, May 10, 2022 — 3:00 PM EDT

## Graphs and Matroids Seminar - Jim Geelen

Title: Connectivity functions and connectivity intertwining

 Speaker: Jim Geelen Affiliation: University of Waterloo Room: MC 5417

Abstract:

Connectivity functions provide a nice way of unifying matroid connectivity with various notions of connectivity in graphs. I will present some new and old open problems.

Monday, May 9, 2022 — 11:30 AM EDT

## Algebraic Graph Theory Seminar - Péter Pál Pach

Title: Polynomials, rank and cap sets

 Speaker: Péter Pál Pach Affiliation: Budapest University of Technology Zoom: Contact Sabrina Lato for link

Abstract:

In this talk we will look at a variant of the polynomial method which was first used to prove that sets avoiding 3-term arithmetic progressions in groups like Z_4^n and F_q^n are exponentially small (compared to the size of the group). We will discuss lower and upper bounds for the size of the extremal subsets.  We will also mention some further applications of the method, for instance, the solution of the Erdős–Szemerédi theorem sunflower conjecture.

Monday, May 2, 2022 — 11:30 AM EDT

## Algebraic Graph Theory Seminar - Weichen Xie

Title: Of Shadows and Gaps in Spatial Search

 Speaker: Weichen Xie Affiliation: Clarkson University Zoom: Contact Sabrina Lato for link

Abstract:

Spatial search occurs in a connected graph if a continuous-time quantum walk on the adjacency matrix of the graph, suitably scaled, plus a rank-one perturbation induced by any vertex will unitarily map the principal eigenvector of the graph to the characteristic vector of the vertex. This phenomenon is a natural continuous-time analogue of Grover search.

Friday, April 29, 2022 — 3:00 PM to Sunday, May 1, 2022 — 6:00 PM EDT

## ASA DataFest - Statistics and Actuarial Science

DataFest 2022 registration is now OPEN!

Register online now!

All members of your team must register.

Monday, April 25, 2022 — 11:30 AM EDT

## Algebraic Graph Theory Seminar - Mahsa N. Shirazi

Title: On the eigenvalues of the perfect matching derangement graph

 Speaker: Mahsa N. Shirazi Affiliation: University of Regina Zoom: Contact Sabrina Lato for link

Abstract:

The perfect matching derangement graph $M_{2n}$ is defined to be the graph whose vertices are all the perfect matchings of the complete graph $K_{2n}$, and two vertices are adjacent if they contain no common edges. The graph $M_{2n}$ is part of a larger study on the analogs of the Erdős-Ko-Rado theorem, and recently there have been interesting works on $M_{2n}$ and its eigenvalues.

Thursday, April 21, 2022 — 11:30 AM EDT

## Cryptography Reading Group - Guiwen Luo

Title: Speeding up Multi-Scalar Multiplication over Fixed Points towards Efficient zkSNARKs

 Speaker: Guiwen Luo Affiliation: University of Waterloo Attend: Contact Jesse Elliott

Abstract:

The arithmetic of computing multiple scalar multiplications in an elliptic curve group then adding them together is called multi-scalar multiplication (MSM). MSM over fixed points dominates the time consumption in pairing-based trusted setup zero-knowledge succinct non-interactive arguments of knowledge (zkSNARKs), thus fast algorithms of MSM over fixed points are desirable for practical applications.

Tuesday, April 19, 2022 — 3:00 PM EDT

## Equity, Diversity, and Inclusion Panel

Join us for a panel discussion focused on understanding and promoting equity, diversity, and inclusion (EDI) in academic settings. All members of our academic communities should strive to create equitable, diverse, and inclusive environments.

Thursday, April 14, 2022 — 1:00 PM EDT

## Algebraic Combinatorics Seminar - Darij Grinberg

Title: The one-sided cycle shuffles in the symmetric group algebra

 Speaker: Darij Grinberg Affiliation: Drexel University Zoom: Contact Logan Crew or Olya Mandelshtam

Abstract:

Elements in the group algebra of a symmetric group S_n are known to have an interpretation in terms of card shuffling. I will discuss a new family of such elements, recently constructed by Nadia Lafrenière: Given a positive integer n, we define n elements t_1, t_2, ..., t_n in

Wednesday, April 13, 2022 — 2:00 PM EDT

## Reading Group Talk - Sean Kafer

Title: Generating Short Monotone Paths in 0/1 LPs: From Circuits to Simplex

 Speaker: Sean Kafer Affiliation: University of Waterloo Zoom: 945 0789 9910 (passcode: kafer)

Abstract:

Even after decades of study, it is unknown whether there exists a pivot rule for the Simplex method that always solves an LP with only a polynomial number of pivots.  This remains unknown even in the special case of 0/1 LPs - i.e., LPs defined over 0/1 polytopes - a case that includes many extensively studied problems in combinatorial optimization.

Tuesday, April 12, 2022 — 3:00 PM EDT

## Graphs and Matroids Seminar - Carolyn Chun

Title: Lattice path matroids, lattice path polymatroids, and excluded minors

 Speaker: Carolyn Chun Affiliation: US Naval Academy Zoom: http://matroidunion.org/?page_id=2477 or contact Shayla Redlin

Abstract:

We define lattice path matroids, polymatroids, Boolean polymatroids, and lattice path polymatroids, which are a subclass of Boolean polymatroids.

Monday, April 11, 2022 — 11:30 AM EDT

## Algebraic Graph Theory Seminar - Victor Wang

Title: Deletion-contraction for a unified Laplacian and applications

 Speaker: Victor Wang Affiliation: University of British Columbia Zoom: Contact Sabrina Lato

Abstract:

We define a graph Laplacian with vertex weights in addition to the more classical edge weights, which unifies the combinatorial Laplacian and the normalised Laplacian.

Thursday, April 7, 2022 — 1:00 PM EDT

## Algebraic Combinatorics Seminar - Farid Aliniaeifard

Title: Modular relations between chromatic symmetric functions

 Speaker: Farid Aliniaeifard Affiliation: University of British Columbia Zoom: Contact Logan Crew or Olya Mandelshtam

Abstract:

In 1995, Stanley introduced the chromatic symmetric functions. The study of chromatic symmetric functions of graphs inspired two main research directions.

Tuesday, April 5, 2022 — 3:00 PM EDT

## Graphs and Matroids Seminar - Lise Turner

Title: A local version of Hadwiger’s Conjecture

 Speaker: Lise Turner Affiliation: University of Waterloo Zoom: http://matroidunion.org/?page_id=2477 or contact Shayla Redlin

Abstract:

In 1943, Hadwiger famously conjectured that graphs with no $K_t$ minors are $t-1$ colourable. There has also been significant interest in several variants of the problem, such as list colouring or only forbidding certain classes of minors.

## Pages

### May 2022

S M T W T F S
3
4
5
6
7
8
11
15
16
18
21
22
23
28
29
30
31
1
2
3
4
1. 2022 (68)
1. June (1)
2. May (15)
3. April (12)
4. March (18)
5. February (10)
6. January (13)
2. 2021 (103)
1. December (3)
2. November (7)
3. October (6)
4. September (12)
5. August (6)
6. July (10)
7. June (12)
8. May (7)
9. April (9)
10. March (13)
11. February (8)
12. January (10)
3. 2020 (119)
4. 2019 (167)
5. 2018 (136)
6. 2017 (103)
7. 2016 (137)
8. 2015 (136)
9. 2014 (88)
10. 2013 (48)
11. 2012 (39)
12. 2011 (36)
13. 2010 (40)
14. 2009 (40)
15. 2008 (39)
16. 2007 (15)