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Please note: The University of Waterloo is closed for all events until further notice.

Welcome to Combinatorics and Optimization

Spring 2020 Undergraduate Research Assistantship Program (URA). ***ON-LINE APPICATIONS OPEN November 1, 2019.***

Tutte's Distinguished Lecture Series

The very successful Tutte's 100th Distinguished Lecture Series has now completed. That success has led to a Tutte Distinguished Lecture once per term. The next lecture will happen in the Spring term.

*Recordings of occurred talks are all available on C&O's YouTube Channel

Grad Studies: Fall 2020 applications now open

1. July 1, 2020C&O welcomes four new faculty members

The C&O department is very pleased to welcome four new faculty members, Assistant Professors Logan Crew, Stephen Melczer, Oliver Pechenik and Sophie Spirkl.

2. June 30, 2020Jun Yan awarded an Alumni Gold Medal

At the Spring convocation, Jun Yan was awarded an Alumni Gold Medal in recognition of his academic excellence during his undergraduate studies in Combinatorics & Optimization and Pure Mathematics. Jun Yan was also a recipient of the 2020 William Tutte Centenary Scholarship.

3. June 27, 2020Jochen Koenemann to begin a two-year term as department chair

On July 1, 2020, Professor Jochen Koenemann begins a two-year term as chair of the Combinatorics and Optimization (C&O) department.

1. July 13, 2020Algebraic Graph Theory Seminar - Sebastian Cioaba

Title: On the flip graph on perfect matchings of complete graphs and sign reversal graphs

 Speaker: Sebastian Cioaba Affiliation: University of Delaware Zoom: Contact Soffia Arnadottir

Abstract:

In this talk, we study the flip graph on the perfect matchings of a complete graph of even order. We investigate its combinatorial and spectral properties including connections to the signed reversal graph and we improve a previous upper bound on its chromatic number.

2. July 16, 2020Algebraic Combinatorics Seminar - Oliver Pechenik

Title: Dynamics of plane partitions

 Speaker: Oliver Pechenik Affiliation: University of Waterloo Zoom: Contact Karen Yeats

Abstract:

Consider a plane partition P in an a X b X c box. The rowmotion operator sends P to the plane partition generated by the minimal elements of its complement. We show rowmotion resonates with frequency a+b+c-1, in the sense that each orbit size shares a prime divisor with a+b+c-1. This confirms a 1995 conjecture of Peter Cameron and Dmitri Fon-Der-Flaass. (Based on joint works with Kevin Dilks & Jessica Striker and with Becky Patrias.)

Title: Two unsolved problems: Birkhoff--von Neumann graphs and PM-compact graphs

 Speaker: Nishad Kothari Affiliation: CSE Department, Indian Institute of Technology Madras Zoom: Contact Sharat Ibrahimpur

Abstract:

A well-studied object in combinatorial optimization is the {\it perfect matching polytope} $\mathcal{PMP}(G)$ of a graph $G$ --- the convex hull of the incidence vectors of all perfect matchings of $G$. A graph $G$ is {\it Birkhoff--von Neumann} if $\mathcal{PMP}(G)$ is characterized solely by non-negativity and degree constraints, and $G$ is {\it PM-compact} if the combinatorial diameter of $\mathcal{PMP}(G)$ equals one.

All upcoming events