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Title: Dyadic matroids with spanning cliques
Speaker: Kevin Grace Affiliation: University of Bristol Room: MC 5479*Please note time and date change
Abstract:
The Matroid Minors Project of Geelen, Gerards, and Whittle describes the structure of minorclosed classes of matroids representable over a fixed finite field.
Title: Mutually unbiased bases
Speaker: Chris Godsil Affiliation: University of Waterloo Room: MC 5479Abstract:
A pair of d x d unitary matrices is unbiased if M*N is at, i.e., all its entries have the same absolute value. A relatively simple argument shows that a set of pairwise unbiased unitary matrices has size at most d + 1.
Title: Fun with Pfaffians: Identities for Schur QFunctions
Speaker: Angele Hamel Affiliation: Wilfrid Laurier University Room: MC 5417Abstract:
Schur functions determinantal identities (e.g. JacobiTrudi, Giambelli) are cornerstones of symmetric function theory. Less wellknown are the Pfaffian identities for Schur Qfunctions.
Title: Quasipopular Matchings, Optimality, and Extended Formulations
Speaker: Kanstantsin Pashkovich Affiliation: University of Waterloo Room: MC 5479Abstract:
The goal of this talk is to obtain efficient algorithms for computing desirable matchings (wrt cost) by paying the price of mildly relaxing popularity.
Title: Feynman graphs to chord diagrams
Speaker: Karen Yeats Affiliation: University of Waterloo Room: MC 5501Abstract:
I will explain how classic techniques of algebraic combinatorics can, via chord diagrams, tell us about the leading log, nexttoleading log, etc, expansions in quantum field theory, and what we think chord diagrams can tell us about individual Feynman graphs as well.
Title: Indicence groups of graphs, forbidden minors, and planar covers
Speaker: William Slofstra Affiliation: University of Waterloo Room: MC 5417Abstract:
The solution group of binary linear system is a quantumprobabilistic generalization of the solution space of the system.
Title: A (1 + 1/e)Approximation Algorithm for Maximum Stable Matching with OneSided Ties and Incomplete Lists
Speaker: Madison Van Dyk Affiliation: University of Waterloo Room: MC 5479Abstract:
We will continue the discussion of stable matching when there are unacceptable pairs and onesided ties. Two weeks ago, we looked at a 3/2approximation that was purely combinatorial.
Title: On the approximability of the stable matching problem with ties of size two and onesided ties
Speaker: Kanstantsin Pashkovich Affiliation: University of Ottawa Room: MC 5501Abstract:
The stable matching problem is central for game theory. If participants are allowed to have ties, the problem of finding a stable matching of maximum cardinality is an NPhard problem, even when the ties are of size two.
Title: From Combinatorics to Computer Algebra and Morse Theory  Making Sense of Multivariate Asymptotics
Speaker: Stephen Melczer Affiliation: University of Pennsylvania Room: MC 5479Abstract:
The asymptotic study of multivariate generating functions comprises the domain of Analytic Combinatorics in Several Variables (ACSV).
Title: Incidence bialgebras of monoidal categories
Speaker: Lucia Rotheray Affiliation: Technische Universität Dresden Room: MC 5417Abstract:
We begin with Joni and Rota's definition of the incidence coalgebra of a category or partially ordered set and then discuss some cases where a monoidal product on a category turns this coalgebra into a bialgebra.
Title: Stable Flows
Speaker: Sharat Ibrahimpur Affiliation: University of Waterloo Room: MC 5479Abstract:
We describe a flow model that generalizes ordinary network flows the same way as stable matchings generalize the bipartite matching problem.
Title: QAOA Versus Classical
Speaker: Mario Szegedy Affiliation: Alibaba Quantum Laboratory Room: MC 5501Abstract:
There has been a back and forth about whether the QAOA algorithm of Farhi, Goldstone and Gutmann can in some sense be duplicated classically.
Title: Reverse plane partitions via quiver representations
Speaker: Hugh Thomas Affiliation: Université du Québec à Montréal Room: MC 5417Abstract:
Let $\lambda$ be a partition. The reverse plane partitions of shape $\lambda$ are a kind of filling of the Ferrers diagram of $\lambda$ by nonnegative integers. Richard Stanley found the generating function which enumerates them according to the sum of the entries.
Title: Graphs in algebra and algebra in graphs
Speaker: Soffia Arnadottir Affiliation: University of Waterloo Room: MC 5501Abstract:
How do algebraic properties of a graph relate to its graph theoretic properties? What are algebraic properties of graphs? What does the spectrum of a graph tell us about its structure? What is a Cayley graph?
Title: Kemeny's Constant for Markov Chains
Speaker: Steve Kirkland Affiliation: University of Manitoba Room: MC 5479Abstract:
Markov chains are a muchstudied class of stochastic processes, and it is wellknown that if the transition matrix A associated with a Markov chain possesses a certain property (called primitivity), then the longterm behaviour of the Markov chain is described by a particular eigenvector of A, known as the stationary distribution vector.
Title: Lewis Carroll and the Red Hot Potato
Speaker: Melanie Dennis Affiliation: Dartmouth College Room: MC 5417Abstract:
The Lewis Carroll identity expresses the determinant of a matrix in terms of subdeterminants obtained by deleting one row and column or a pair of rows and columns.
Title: New and Simple Algorithms for Stable Flow Problems
Speaker: Justin Toth Affiliation: University of Waterloo Room: MC 5479Abstract:
In the previous reading group talk we defined stable flows and saw that they always exist by a reduction to the stable allocation problem.
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