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:
Monday, October 5, 2020 11:30 am - 11:30 am EDT (GMT -04:00)

Algebraic Graph Theory Seminar - Brendan Rooney

Title: Efficient $(j,k)$-Domination

Speaker: Brendan Rooney
Affiliation: Rochester Institute of Technology
Zoom: Contact Soffia Arnadottir

Abstract:

A function $f:V(G)\rightarrow\{0,\ldots,j\}$ is an efficient $(j,k)$-dominating function on $G$ if $\sum_{u\in N[v]}f(u)=k$ for all $v\in V(G)$ (here $N[v]=N(v)\cup\{v\}$ is the closed neighbourhood of $v$).

Thursday, October 8, 2020 1:00 pm - 1:00 pm EDT (GMT -04:00)

Algebraic Combinatorics Seminar - Alejandro Morales

Title: Factorization problems in complex reflection groups

Speaker: Alejandro Morales
Affiliation: University of Massachusetts Amherst
Zoom: Contact Karen Yeats

Abstract:

The study of factorizations in the symmetric group is related to combinatorial objects like graphs embedded on surfaces and non-crossing partitions. We consider analogues for complex reflections groups of certain factorization problems of permutations first studied by Jackson, Schaeffer, Vassilieva and Bernardi.

Monday, October 19, 2020 11:30 am - 11:30 am EDT (GMT -04:00)

Algebraic Graph Theory Seminar - Christopher van Bommel

Title: Pretty Good State Transfer and Minimal Polynomials

Speaker: Christopher van Bommel
Affiliation: University of Manitoba
Zoom: Contact Soffia Arnadottir

Abstract:

We examine conditions for a pair of strongly cospectral vertices to have pretty good quantum state transfer in terms of minimal polynomials, and provide cases where pretty good state transfer can be ruled out.

Monday, October 19, 2020 3:00 pm - 3:00 pm EDT (GMT -04:00)

Graphs and Matroids Seminar - Erik Panzer

Title: The Hepp bound of a matroid: flags, volumes and integrals

Speaker: Erik Panzer
Affiliation: University of Oxford
Zoom: Contact Rose McCarty

Abstract:

Invariants of combinatorial structures can be very useful tools that capture some specific characteristics, and repackage them in a meaningful way. For example, the famous Tutte polynomial of a matroid or graph tracks the rank statistics of its submatroids, which has many applications, and relations like contraction-deletion establish a very close connection between the algebraic structure of the invariant (e.g. Tutte polynomials) and the actual matroid itself.

Wednesday, October 21, 2020 4:30 pm - 4:30 pm EDT (GMT -04:00)

Joint Colloquium PMath+CO - Nick Olson-Harris

Title: On the Theory of the Analytical Forms called Trees

Speaker: Nick Olson-Harris
Affiliation: University of Waterloo
Zoom: Contact Maxwell Levit

Abstract:

Trees are among the most fundamental of combinatorial structures. Nowadays they appear all over mathematics and computer science, but this has not always been the case. Trees were first introduced, at least under that name, in an 1857 paper of Cayley by the same title as this talk.

Thursday, October 22, 2020 1:00 pm - 1:00 pm EDT (GMT -04:00)

Algebraic Combinatorics Seminar - Reuven Hodges

Title: Coxeter combinatorics and spherical Schubert geometry

Speaker: Reuven Hodges
Affiliation: University of Illinois
Zoom: Contact Karen Yeats

Abstract:

This talk will introduce spherical elements in a finite Coxeter system. These spherical elements are a generalization of Coxeter elements, that conjecturally, for Weyl groups, index Schubert varieties in the flag variety G/B that are spherical for the action of a Levi subgroup.

Monday, October 26, 2020 11:30 am - 11:30 am EDT (GMT -04:00)

Algebraic Graph Theory Seminar - Ferdinand Ihringer

Title: Pseuodrandom Cliquefree Graphs, Finite Geometry, and Spectra

Speaker: Ferdinand Ihringer
Affiliation: Ghent University, Belgium
Zoom: Contact Soffia Arnadottir

Abstract:

A regular graph is called optimally pseudorandom if its second largest eigenvalue in absolute value is, up to a constant factor, as small as possible. Determining the largest degree of an optimally pseudorandom graph without a clique of size s is a well-known open problem in extremal graph theory.

Thursday, October 29, 2020 1:00 pm - 1:00 pm EDT (GMT -04:00)

Algebraic Combinatorics Seminar - Florian Aigner

Title: qRSt: A probabilistic Robinson--Schensted correspondence for Macdonald polynomials

Speaker: Florian Aigner
Affiliation: Université du Québec à Montréal
Zoom: Contact Karen Yeats

Abstract:

The Robinson--Schensted (RS) correspondence is a bijection between permutations and pairs of standard Young tableaux which plays a central role in the theory of Schur polynomials. In this talk, I will present a (q,t)-dependent probabilistic deformation of Robinson--Schensted which is related to the Cauchy identity for Macdonald polynomials.

Friday, October 30, 2020 3:30 pm - 3:30 pm EDT (GMT -04:00)

Tutte Colloquium - Logan Crew

Title: The Tutte Symmetric Function

Speaker: Logan Crew
Affiliation: University of Waterloo
Zoom: Please email Emma Watson

Abstract:

The Tutte polynomial is one of the most celebrated and most well-studied graph functions, in part because it specializes to every graph polynomial with a linear deletion-contraction relation, such as the chromatic polynomial. In the 1990s, Stanley generalized the Tutte polynomial to a symmetric function, but at the cost of the deletion-contraction relation.

Monday, November 2, 2020 11:30 am - 11:30 am EST (GMT -05:00)

Algebraic Graph Theory Seminar - Sabrina Lato & Christino Tamon

Title: Monogamy Violations in Perfect State Transfer

Speakers: Sabrina Lato & Christino Tamon
Affiliations: University of Waterloo & Clarkson Unversity
Zoom: Contact Soffia Arnadottir

Abstract:

Continuous-time quantum walks on a graph are defined using a Hermitian matrix associated to a graph. For a quantum walk on a graph using either the adjacency matrix or the Laplacian, there can be perfect state transfer from a vertex to at most one other vertex in the graph.