Welcome to Combinatorics and Optimization
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.
New Deadline: February 1, '20
- May 5, 2021
Olya Mandelshtam and Kanstantsin Pashkovich are the newest faculty members in the C&O department.
- May 4, 2021
Professor Henry Wolkowicz is a co-organizer of an upcoming Workshop on Discrete Geometry, Semidefinite Programming and Applications (May 10-14) and a Mini-Symposium on Sensor Network Localization and Dynamical Distance Geometry (May 18-27).
- Apr. 27, 2021
In her paper, the 1989 Erdos-Hajnal conjecture is resolved for cycles of length 5.
- May 17, 2021
Title: Minimum eigenvalue of nonbipartite graphs
Speaker: Bojan Mohar Affiliation: Simon Fraser University Zoom: Contact Soffia Arnadottir
Let \rho and \lambda be the largest and the smallest eigenvalue of a connected graph G. It is well-known that \rho + \lambda \geq 0 and that equality occurs if and only if G is bipartite. The speaker will discuss what else can we say when G is not bipartite.
- May 20, 2021
Title: q-Whittaker functions, finite fields, and Jordan forms
Speaker: Steven Karp Affiliation: UQAM Zoom: Contact Steve Melczer
The q-Whittaker symmetric function associated to an integer partition is a q-analogue of the Schur symmetric function. We give a new formula for the q-Whittaker function in terms of partial flags compatible with a nilpotent endomorphism over the finite field of size 1/q.
- May 21, 2021
Title: Positivity Problems for Linear Recurrences
Speaker: Steve Melczer Affliliation: University of Waterloo Zoom: Contact Emma Watson
Although sequences satisfying linear recurrence relations have been studied for centuries, and appear as some of the first examples of combinatorial sequences encountered in an introductory combinatorics class, there are natural examples of simply stated problems related to their basic behaviour whose decidability is unknown. In this talk we survey some open computability and complexity questions related to the positivity of linearly recurrent sequences, before examining a new approach to proving positivity using rigorous numerical methods for functions satisfying linear differential equations.