University COVID-19 update

The University of Waterloo is constantly updating our most Frequently Asked Questions.

Questions about buildings and services? Visit the list of Modified Services.

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

Welcome to Combinatorics and Optimization

Winter 2020 Undergraduate Research Assistantship (URA) Opportunities.

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

 New Deadline: February 1, '20

  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
    Jun Yan

    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
    Jochen Koenemann

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

Read all news
  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


    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


    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.)

  3. July 17, 2020Combinatorial Optimization Reading Group - Nishad Kothari

    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


    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