Contact Info
Combinatorics & Optimization
University of Waterloo
Waterloo, Ontario
Canada N2L 3G1
Phone: 519-888-4567, ext 33038
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Friday, March 13, 2020 — 3:30 PM EDT
Title: Widths in even-hole-free graphs
| Speaker: | Nicolas Trotignon |
| Affiliation: | École Normale Supérieure de Lyon |
| Room: | MC 5501 |
Abstract:
Historically, the study of even-hole-free graphs is motivated by the analogy with perfect graphs. The decomposition theorems that are known for even-hole-free graphs are seemingly more powerful than the ones for perfect graphs: the basic classes and the decompositions are more restricted.
Friday, March 13, 2020 — 1:00 PM EDT
Title:
| Speaker: | Harry Sivasubramaniam |
| Affiliation: | University of Waterloo |
| Room: | MC 5417 |
Abstract:
Differential privacy is about preserving an individuals privacy while maintaining utility in the context of data analysis.
Thursday, March 12, 2020 — 4:00 PM EDT
Title: Improving the general upper bound for Hadwiger's conjecture
| Speaker: | Luke Postle |
| Affiliation: | University of Waterloo |
| Room: | MC 5479 |
Abstract:
In 1943, Hadwiger conjectured that every K_t-minor-free graph has chromatic number at most t-1.
Thursday, March 12, 2020 — 2:30 PM EDT
Title: Proof of the monotone column permanent conjecture
| Speaker: | David Wagner |
| Affiliation: | University of Waterloo |
| Room: | MC 5417 |
Abstract:
In 1993, Jim Haglund conjectured the following. If A is a square matrix of real numbers which are weakly decreasing down each column, and J is the all-ones matrix of the same size, then the permanent of the matrix xJ+A is a polynomial with only real roots.
Tuesday, March 10, 2020 — 8:42 AM EDT
Title: Rectangular Catalan Algebraic Combinatorics
| Speaker | François Bergeron |
| Affiliation | LACIM - Université du Québec à Montréal |
| Room | MC 5501 |
Abstract:
The enumeration of Dyck-like lattice paths in a m x n rectangle has a long and fruitful history culminating in Bizley-Grossman’s formula (1954). We will discuss how it is natural to extend this formula to weighted enumeration, with parameters accounting for such statistics as area; and to consider parking-function analogs.
Friday, March 6, 2020 — 3:30 PM EST
Title: Binary Submatroids
| Speaker: | Peter Nelson |
| Affiliation: | University of Waterloo |
| Room: | MC 5501 |
Abstract:
A binary matroid can be thought of as a set of nonzero binary vectors.
Friday, March 6, 2020 — 1:00 PM EST
Title: Recognizing slack matrices
| Speaker: | Matt Gerstbrein |
| Affiliation: | University of Waterloo |
| Room: | MC 5417 |
Abstract:
This week, we will be discussing the topic of slack matrices. Slack matrices arise in the context of lifts of polytopes, where, given a polytope P, we can characterize the existence of a lift of P of a given size in terms of properties of an associated slack matrix.
Thursday, March 5, 2020 — 2:30 PM EST
Title: Combinatorial Hall algebras
| Speaker: | Matt Szczesny |
| Affiliation: | Boston University |
| Room: | MC 5417 |
Abstract:
The Hall algebra of a finitary category is an associative (and sometimes Hopf) algebra whose structure constants count the number of extensions between objects.
Thursday, March 5, 2020 — 1:00 PM EST
Title: Strongly cospectral vertices in cubelike graphs
| Speaker: | Soffia Arnadottir |
| Affiliation: | University of Waterloo |
| Room: | MC 5417 |
Abstract:
A cubelike graph is a Cayley graph of the elementary abelian 2-group. Two vertices in a graph are strongly copsectral if they are cospectral and parallel.
Wednesday, March 4, 2020 — 2:00 PM EST
Title: Vertex-minors and sparsity
| Speaker: | Rose McCarty |
| Affiliation: | University of Waterloo |
| Room: | MC 5479 |
Abstract:
We discuss an ongoing project with Jim Geelen and Paul Wollan to describe the structure of graph classes excluding a vertex-minor.
Tuesday, March 3, 2020 — 1:15 PM EST
Title: Introduction to Monotone Operators
| Speaker: | Naomi Graham |
| Affiliation: | University of Waterloo |
| Room: | MC 5501 |
Abstract:
This talk will be an entry level introduction to the theory of monotone operators as they are presented in Bauschke and Combette’s Convex Analysis and Monotone Operator Theory in Hilbert Spaces.