Events by month

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.