Contact Info
Combinatorics & Optimization
University of Waterloo
Waterloo, Ontario
Canada N2L 3G1
Phone: 5198884567, ext 33038
PDF files require Adobe Acrobat Reader.
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Title: The $k$Independence Number
Speaker: Lord Kavi Affiliation: University of Ottawa Zoom: Contact Soffia ArnadottirAbstract:
An independent set, also known as a stable set or coclique, in a graph is a set of vertices, no two of which are adjacent. The size of a largest independent set is called the independence number. Two classical eigenvalue bounds on the independence number, proved using eigenvalue interlacing are the Hoffman's ratio bound and the Cvetkovi\'{c}'s inertia bound.
Title: Asymptotic quantum state transfer using two loops with large weights
Speaker: Gabor Lippner Affiliation: Northeastern University Zoom: Contact Soffia ArnadottirAbstract:
We study the question of asymptotic transfer strength between two nodes of a graph when large weight loop edges are located at these nodes. It turns out that the limiting strength can be exactly computed and depends only on the extended neighborhoods of the nodes.
Title: Two conjectures on the spread of graphs
Speaker: Michael Tait Affiliation: Villanova University Zoom: Contact Soffia ArnadottirAbstract:
Given a graph $G$ let $\lambda_1$ and $\lambda_n$ be the maximum and minimum eigenvalues of its adjacency matrix and define the spread of $G$ to be $\lambda_1  \lambda_n$. In this talk we discuss solutions to a pair of 20 year old conjectures of Gregory, Hershkowitz, and Kirkland regarding the spread of graphs.
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/an21Description
Title: In Memoriam: Tom Coleman’s Contributions to Applied Mathematics and Optimization
Speakers: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/an21Description:
Thomas F. Coleman—a leader in optimization and scientific computing, professor at the University of Waterloo, and a SIAM Fellow—passed away on April 20, 2021. Tom served as the Director of the Theory Center at Cornell and then as Dean of the Faculty of Mathematics at the University of Waterloo. His research spanned continuous optimization, combinatorial scientific computing, automatic differentiation, financial optimization, mathematical software, etc. In this session, his wife and collaborator, Yuying Li, and five of his students and colleagues will describe the pioneering contributions that Tom made to these fields in his research.
Title: The spectrum of the randomtobelow Markov chain
Speaker: Nadia Lafrenière Affiliation: Dartmouth College Zoom: Contact Stephen MelczerAbstract:
The randomtobelow shuffle of a deck of cards consists of removing any card randomly (with uniform probability), and inserting it anywhere below (with uniform probability). When looking at the eigenvalues of its transition matrix, they all seem to be rational and positive.
Title: Algebraic formulations of Zauner's conjecture
Speaker: Jon Yard Affiliation: University of Waterloo Zoom: Please email Emma WatsonAbstract:
Tight complex projective 2designs are simultaneously maximal sets of equiangular lines and minimal complex projective 2designs. In quantum information theory, they define optimal measurements known as SICPOVMs (Symmetric Informationally Complete Positive OperatorValued 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 finitebutgrowing list of dimensions via exact, explicit constructions over increasingly highdegree number fields, since identified as specific class fields of real quadratic number fields.
Title: Equivalent Laplacian and Adjacency Quantum Walks on Irregular Graphs
Speaker: Thomas Wong Affiliation: Creighton University Zoom: Contact Soffia ArnadottirAbstract:
The continuoustime 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: A primaldual interiorpoint algorithm fo rnonsymmetric conic optimization
Speaker: Erling D. Andersen Affiliation: Mosek ApS Zoom: Register through The Fields InstituteAbstract:
It is well known that primaldual interiorpoint algorithms for linear optimization can easily be extended to the case of symmetric conic optimization, as shown by Nesterov and Todd (NT) in their 1997 paer about selfscaled barriers. Although many convex optimization problems can be expressed using symmetric cones then models involving for instance exponential functions do not belong to the class of symmetric conic optimization problems.
Title: Macdonald polynomials and the multispecies zero range process
Speaker: Olya Mandelshtam Affiliation: University of Waterloo Zoom: Please email Emma WatsonAbstract:
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 wellstudied 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.
Combinatorics & Optimization
University of Waterloo
Waterloo, Ontario
Canada N2L 3G1
Phone: 5198884567, ext 33038
PDF files require Adobe Acrobat Reader.
The University of Waterloo acknowledges that much of our work takes place on the traditional territory of the Neutral, Anishinaabeg and Haudenosaunee peoples. Our main campus is situated on the Haldimand Tract, the land granted to the Six Nations that includes six miles on each side of the Grand River. Our active work toward reconciliation takes place across our campuses through research, learning, teaching, and community building, and is centralized within our Indigenous Initiatives Office.