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

# Welcome to Combinatorics and Optimization

Spring 2021 Undergraduate Research Assistantship Program (URA). ***ON-LINE APPICATIONS OPEN November 9, 2020 - December 15, 2020.***

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. Nov. 13, 2020Collaborating to advance quantum technologies in Canada and the UK

Earlier this year, Canada and the United Kingdom (UK) joined together to put a call out for proposals of collaborations between leading-edge scientists and potential innovative users from industry and government sectors to accelerate the development of quantum technologies.

2. Nov. 12, 2020Unsolved puzzles

“When I was a kid, I always begged my parents to buy me those little Mind Benders puzzles,” remembered Rose McCarty. “My favorite puzzles were the ones that were so difficult that I wasn’t sure whether or not I could actually solve them. At Waterloo Math, I’m the one coming up with different puzzles to solve. I have an opportunity to tackle big, imprecise, unwieldly problems that determine what my field will look like in 20 years.”

3. Oct. 30, 2020A secret hero's cyber legacy

Craig Daniels, in an article for Communitech News, traces the rise of the cybersecurity industry in Waterloo, from Bill Tutte's work at Bletchley Park during the Second World War, to the formation of Certicom Corp. by Professors Gord Agnew, Ron Mullin and Scott Vanstone, to the present time.

1. Dec. 7, 2020Algebraic Graph Theory Seminar - Shahla Nasserasr

Title: Distinct Eignvalues and Sensitivity

 Speaker: Shahla Nasserasr Affiliation: Rochester Institute of Technology Zoom: Contact Soffia Arnadottir

Abstract:

For a graph $G$, the class of real-valued symmetric matrices whose zero-nonzero pattern of off-diagonal entries is described by the adjacencies in $G$ is denoted by $S(G)$. The inverse eigenvalue problem for the multiplicities of the eigenvalues of $G$ is to determine for which ordered list of positive integers $m_1\geq m_2\geq \cdots\geq m_k$ with $\sum_{i=1}^{k} m_i=|V(G)|$, there exists a matrix in $S(G)$ with distinct eigenvalues ${\lambda_1,\lambda_2,\cdots, \lambda_k}$ such that $\lambda_i$ has multiplicity $m_i$.

2. Dec. 10, 2020Algebraic Combinatorics Seminar - Laura Colmenarejo

Title: Chromatic symmetric functions of Dyck paths and $q$-rook theory

 Speaker: Laura Colmenarejo Affiliation: UMass Amherst Zoom: Contact Karen Yeats

Abstract:

Given a graph and a set of colors, a coloring of the graph is a function that associates each vertex in the graph with a color. In 1995, Stanley generalized this definition to symmetric functions by looking at the number of times each color is used and extending the set of colors to $\mathbb{Z}^+$. In 2012, Shareshian and Wachs introduced a refinement of the chromatic functions for ordered graphs as $q$-analogues.

3. Dec. 11, 2020Tutte Colloquium - Santanu Dey

Title: Sparse PSD approximation of the PSD cone

 Speaker: Santanu Dey Affiliation: H. Milton Stewart School of Industrial and Systems Engineering at Georgia Institute of Technology Zoom: Please email Emma Watson

Abstract:

While semidefinite programming (SDP) problems are polynomially solvable in theory, it is often difficult to solve large SDP instances in practice. One computational technique used to address this issue is to relax the global positive-semidefiniteness (PSD) constraint and only enforce PSD-ness on smaller k × k principal submatrices — we call this the sparse SDP relaxation.

All upcoming events