Welcome to Combinatorics and Optimization

The C&O department has 33 faculty members and 60 graduate students. We are intensely research oriented and hold a strong international reputation in each of our six major areas:

Read more about the department's research to learn of our contributions to the world of mathematics!

Two Tenure-Track Faculty Positions Available in C&O

Visit our Career opportunities page for more details. 

  1. Nov. 17, 2021Michael J. Best (1946-2021)
    Michael J Best

    We are saddened to announce that our colleague and friend Michael Best, Professor of Combinatorics and Optimization at University of Waterloo, passed away on November 10 after a battle with cancer.

  2. Oct. 13, 2021Fall 2021 convocation
    Convocation Fall 2021

    Five Ph.D. and four M.Math. C&O students will receive their degrees at the Fall 2021 convocation on October 22.

  3. Oct. 7, 2021C&O M.Math. student wins a gold medal at ICPC 2021
    Dmitry Sayutin

    Dmitry Sayutin's team at the ITMO University in St. Petersburg won a gold medal at ICPC 2021.

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  1. Jan. 21, 2022Tutte Colloquium - Manuel Kauers

    Title: Guessing with little data

    Speaker: Manuel Kauers
    Affiliation: Johannes Kepler University
    Zoom: Please email Emma Watson


    A popular and powerful technique in experimental mathematics takes as input the first few terms of an infinite sequence and returns plausible candidates for recurrence equations that the sequence may satisfy. In a way, the search for such candidates is a generalization of polynomial interpolation. For polynomial interpolation, it is well known and easy to see that d+1 sample points are needed in order to recover a polynomial of degree d. Similarly, it turns out that (r+1)*(d+2) consecutive terms of a sequence are needed in order to detect a linear recurrence of order r with polynomial coefficients of degree at most d.

  2. Jan. 24, 2022Algebraic Graph Theory Seminar - Erika Pirnes

    Title: Minimal relations for an algebra inspired by algebraic graph theory

    Speaker: Erika Pirnes
    Affiliation: University of Wisconsin-Madison
    Zoom: Contact Sabrina Lato


    The balanced algebra has two generators, R and L, and its defining relations are that any pair of balanced words commutes. For example, RL and LR are balanced (contain the same number of both generators), so in the balanced algebra, (RL)(LR)=(LR)(RL).

  3. Jan. 25, 2022Graphs and Matroids Seminar - Archontia Giannopoulou

    Title: A Matching Theoretic Flat Wall Theorem

    Speaker: Archontia Giannopoulou
    Affiliation: University of Athens
    Zoom: http://matroidunion.org/?page_id=2477 or please email Shayla Redlin


    One of the key theorems in Graph Minors is the Flat Wall Theorem which asserts the existence of a large wall under certain conditions. In this talk, we discuss about graphs with perfect matchings and their relationship with digraphs. Our main focus is on a matching theoretic analogue of the Flat Wall Theorem for bipartite graphs excluding a fixed matching minor.

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