Events

Filter by:

Limit to events where the first date of the event:
Date range
Limit to events where the first date of the event:
Limit to events where the title matches:
Limit to events where the type is one or more of:
Limit to events tagged with one or more of:
Limit to events where the audience is one or more of:
Tuesday, June 18, 2024 3:00 pm - 4:00 pm EDT (GMT -04:00)

Graphs and Matroids Seminar - Thomas Lesgourgues

Title: Ramsey with purple edges

Speaker: Thomas Lesgourgues
Affiliation: University of Waterloo
Location: MC 5479

Abstract: Motivated by a question of David Angell, we study a variant of Ramsey numbers where some edges are coloured with both red and blue colours, (i.e. are called ‘purple’ edges). Specifically, we are interested in the largest number g = g(s, t, n), for some s and t and n < R(s, t), such that there exists a red-blue-purple colouring of Kn with g purple edges, without a red-purple Ks and without a blue-purple Kt. We determine g asymptotically for a large family of parameters. The talk will be introductory in nature. Since the concept of double-coloured edges is new in this context, there is a plethora of open questions. Joint work with Anita Liebenau and Nye Taylor.

Friday, June 21, 2024 3:30 pm - 4:30 pm EDT (GMT -04:00)

Tutte Colloquium - Paul Balduf

Title: Graph theory and Feynman integrals

Speaker: Paul Balduf
Affiliation: University of Waterloo
Location: MC 5501

Abstract: Feynman integrals are one of the most versatile tools in theoretical physics. They are used to compute perturbative solutions for various interacting systems. Examples include scattering amplitudes in quantum field theory, gravitational waves at black hole mergers, and the scaling behavior in statistical physics at critical points. Every Feynman integral is defined in terms of a corresponding Feynman graph, and besides the concrete physical application, it is interesting to study the number theory of Feynman integrals and how they are related to combinatorial properties of the underlying graph. What can we know about the value of the integral from examining the graph alone? In particular: Under which conditions will the Feynman integrals of two non-isomorphic graphs evaluate to the same number?

Friday, June 28, 2024 3:30 pm - 4:30 pm EDT (GMT -04:00)

Tutte Colloquium - Jason Gao

Title: Graph Embeddings and Map Colorings

Speaker: Jason Gao
Affiliation: Carleton University
Location: MC 5501

Abstract: The famous  Map Color Theorem says that the chromatic number of a surface of Euler characteristic $c<0$ is equal to $\displaystyle \left\lfloor \frac{1}{2}\left(7+\sqrt{49-24c}\right)\right\rfloor $. This was proved in 1969 by Ringel and Youngs who showed that $K_n$ can be embedded on surfaces of Euler characteristic $c$ such that $\displaystyle n= \left\lfloor \frac{1}{2}\left(7+\sqrt{49-24c}\right)\right\rfloor $. This leads to the study about the  genus distribution of a graph $G$, that is, the number of embeddings of $G$ on surfaces. This talk will go through some recent results about genus distributions of bouquets and cubic graphs.  Some results and conjectures will also be given about the distribution of the  chromatic number of a random map on a given surface.

Wednesday, July 17, 2024 - Friday, July 19, 2024 (all day)

Fulkerson 100

Delbert Ray Fulkerson

Fulkerson 100 is a workshop organized by the Dept. of Combinatorics & Optimization (C&O) from July 17-19, 2024 at the University of Waterloo, to celebrate Fulkerson's legacy and impact in discrete mathematics, especially in the fields of graph theory, optimization, and operations research. Fulkerson 100 will feature invited talks in graph theory, combinatorics, optimization, and theoretical computer science, given by some of the foremost researchers in these areas, as well as lightning talks and a poster session devoted to students and postdocs. By bringing together various leading researchers in discrete mathematics with junior researchers and students, the workshop aims to boost research in the areas pioneered by Fulkerson, while commemorating his vision and contributions.