Algebraic Graph Theory Seminar - Judi McDonald
Title: Skew Adjacency Matrices: The Number of Characteristic polynomials of Skew Cacti
| Speaker: | Judi McDonald |
| Affiliation: | Washington State University |
| Zoom: | Contact Soffia Arnadottir |
Abstract:
Title: Skew Adjacency Matrices: The Number of Characteristic polynomials of Skew Cacti
| Speaker: | Judi McDonald |
| Affiliation: | Washington State University |
| Zoom: | Contact Soffia Arnadottir |
Abstract:
July 28 was the date of the first presentation of the new: "Optimization: Theory, Algorithms, Applications Lecture Series" organized by The Fields Institute and the Department of Combinatorics and Optimization.
Title: Dyadic Linear Programming
| Speaker: | Ahmad Abdi |
| Affiliation: | London School of Economics |
| Zoom: | Please email Emma Watson |
Abstract:
Most linear programming solvers use fixed-precision floating points to approximate the rational numbers. Though successful on most real-world instances, solvers sometimes run into serious issues when carrying out sequential floating-point arithmetic, due to compounded error terms. This practical limitation leads to the following theoretical problem:
Title: The average search probability in a quantum walk with an oracle
| Speaker: | Harmony Zhan |
| Affiliation: | York University |
| Zoom: | Contact Soffia Arnadottir |
Abstract:
Some quantum search algorithms can be viewed as discrete-time quantum walks on graphs with a marked vertex a. In such a walk, the oracle is part of the transition matrix, the target state is the characteristic vector of the outgoing arcs of a, and the initial state is the all-ones vector.
Title: The size Ramsey numbers of graphs and hypergraphs
| Speaker: | Liana Yepremyan |
| Affiliation: | London School of Economics |
| Zoom: | Please email Emma Watson |
Abstract:
The s-colour size-Ramsey number of a graph ( hypergraph) H is the minimum number of edges in a graph (hypergraph) G whose every s-edge-colouring contains a monochromatic copy of H. While the study of size Ramsey numbers for graphs goes back to 70's to the work of Erdos, Faudree, Rousseau and Schelp, the systematic study of these numbers for hypergraphs have been initiated much more recently in 2017 by Dudek, La Fleur, Mubayi, and Rödl. In this talk we will present the current known results in the literature, and some recent progress we have made on several questions in the area.
Title: Macdonald polynomials and the multispecies zero range process
| Speaker: | Olya Mandelshtam |
| Affiliation: | University of Waterloo |
| Zoom: | Please email Emma Watson |
Abstract:
Over the last couple of decades, the theory of special functions and symmetric functions have found unexpected connections to various interacting particle systems. Macdonald polynomials are a family of symmetric functions that are known to have remarkable connections to a well-studied particle model called the ASEP. It is natural to ask whether the modified Macdonald polynomials can be obtained using a combinatorial gadget for some other particle system.
Title: Equivalent Laplacian and Adjacency Quantum Walks on Irregular Graphs
| Speaker: | Thomas Wong |
| Affiliation: | Creighton University |
| Zoom: | Contact Soffia Arnadottir |
Abstract:
The continuous-time quantum walk is a particle evolving by Schrödinger's equation in discrete space. Encoding the space as a graph of vertices and edges, the Hamiltonian is proportional to the discrete Laplacian. In some physical systems, however, the Hamiltonian is proportional to the adjacency matrix instead.
Title: In Memoriam: Tom Coleman’s Contributions to Applied Mathematics and Optimization
| Speaker: | Yuying Li, Stephen Wright, Alex Pothen, Bruce Hendrickson, Peter Forsyth, and Somayeh Moazeni |
| Affiliation: | SIAM Annual Meeting (AN21) |
| Registration: | https://www.siam.org/conferences/cm/conference/an21 |
Description
Title: Algebraic formulations of Zauner's conjecture
| Speaker: | Jon Yard |
| Affiliation: | University of Waterloo |
| Zoom: | Please email Emma Watson |
Abstract:
Tight complex projective 2-designs are simultaneously maximal sets of equiangular lines and minimal complex projective 2-designs. In quantum information theory, they define optimal measurements known as SIC-POVMs (Symmetric Informationally Complete Positive Operator-Valued Measures). They are conjectured by Zauner to exist in every dimension, even as specific group orbits. Yet, they have only so far been proven to exist in a finite-but-growing list of dimensions via exact, explicit constructions over increasingly high-degree number fields, since identified as specific class fields of real quadratic number fields.
Title: HiGHS: Theory, software and Impact
| Speaker: | Julian Hall |
| Affiliation: | University of Edinburgh |
| Zoom: | Register through The Fields Institute |
Abstract:
Since Dantzig formulated the simplex algorithm in 1947, the widespread need to solve linear optimization problems drove the development of algorithmic and computational techniques for decades, yielding several high performance commercial and open source software systems. This talk will focus on the Edinburgh-based work on solving large scale sparse linear programming problems that underpins the high performance open source linear optimization software, HiGHS, the challenges of developing such software, and the Impact that it has achieved.