Contact Info
Combinatorics & Optimization
University of Waterloo
Waterloo, Ontario
Canada N2L 3G1
Phone: 519-888-4567, ext 33038
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Friday, July 6, 2018 3:30 PM EDT
Title: The coloring problem for restricted graph classes
| Speaker: | Chinh T. Hoang |
| Affiliation: | Wilfred Laurier University |
| Room: | MC 5501 |
Abstract:
Let L be a set of graphs. Free(L) is the set of graphs that do not contain any graph in L as an induced subgraph.
Thursday, July 5, 2018 3:30 PM EDT
Title:Generalizing the problem of packing disjoint cycles
| Speaker: | Paul Wollan |
| Affiliation: | University of Rome "La Sapienza" |
| Room: | MC 5479 |
Abstract: A classic result of Erdos and Posa states that there exists a function f such that for all k,
Thursday, July 5, 2018 1:30 PM EDT
Title: Edge State Transfer
| Speaker: | Tina Chen |
| Affiliation: | University of Waterloo |
| Room: | MC 6486 |
Abstract: Most research about quantum state transfer on graphs use adjacency matrices as their Hamiltonians and investigate the transfers between single vertex states.
Friday, June 29, 2018 3:30 PM EDT
Title: The c2 invariant at p=2 by counting edge bipartitions
| Speaker: | Karen Yeats |
| Affiliation: | University of Waterloo |
| Room: | MC 5501 |
Abstract:
Since no one provided a visitor or volunteered for this week, I will explain how to prove a special case of a conjecture about the c2 invariant.
Thursday, June 28, 2018 3:30 PM EDT
Title: Stretching drawings of graphs
| Speaker: | Alan Arroyo |
| Affiliation: | University of Waterloo |
| Room: | MC 5479 |
Abstract: Given a drawing D of a graph (where vertices are dots in the plane and edges are arbitrary curves connecting some pairs of dots),
Thursday, June 28, 2018 11:30 AM EDT
Title: The Many Faces of Circulation Algebras
| Speaker: | Nick Olson-Harris |
| Affiliation: | University of Waterloo |
| Room: | MC 6486 |
Abstract: The circulation algebra is a commutative graded algebra associated to a graph, introduced by Wagner in 1998 to study flows.
Friday, June 22, 2018 3:30 PM EDT
Title: Two-level polytopes
| Speaker: | Kanstantsin Pashkovich |
| Affiliation: | University of Waterloo |
| Room: | MC 5501 |
Abstract:
This talk is dedicated to two-level polytopes. On one side, two-level polytopes form a well structured family of polytopes.
Thursday, June 21, 2018 3:30 PM EDT
Title: The price of connectivity for domination
| Speaker: | Paul Ouvrard |
| Affiliation: | University of Bordeaux |
| Room: | MC 5479 |
Abstract: The price of connectivity for dominating set in a graph G is the ratio between the minimum sizes of a connected dominating set and a dominating set of G.
Tuesday, June 19, 2018 3:00 PM EDT
Title: Minimization of convex compositions
| Speaker: | Courtney Paquette |
| Affiliation: | Lehigh University |
| Room: | MC 6486 |
Abstract:
Numerous optimization tasks can be posed as minimization of a finite convex function composed with a smooth map. Phase retrieval and matrix factorization problems are common examples.
Friday, June 15, 2018 3:30 PM EDT
Title: Distributed coloring in planar graphs
| Speaker: | Marthe Bonamy |
| Affiliation: | University of Bordeaux |
| Room: | MC 5501 |
Abstract:
We are concerned with efficiently coloring sparse graphs in the distributed setting with as few colors as possible. According to the celebrated Four Color Theorem, planar graphs can be colored with at most 4 colors, and the proof gives a (sequential) quadratic algorithm finding such a coloring.
Thursday, June 14, 2018 3:30 PM EDT
Title: Hamilton cycles in cubic planar graphs
| Speaker: | Frantisek Kardos |
| Affiliation: | University of Bordeaux |
| Room: | MC 5479 |
Abstract: Tait conjectured in 1884 that each cubic planar graph contains a Hamilton cycle. Had the conjecture been true,
Tuesday, June 12, 2018 1:00 PM EDT
Title: On isogeny graphs of supersingular elliptic curves over finite fields- Part 2
| Speaker: | Gora Adj |
| Affiliation: | University of Waterloo |
| Room: | MC 6486 |
Abstract: After having defined the supersingular isogeny graph, in this second talk
Friday, June 8, 2018 3:30 PM EDT
Title: Online Learning of Quantum States
| Speaker: | Ashwin Nayak |
| Affiliation: | University of Waterloo |
| Room: | MC 5501 |
Abstract:
Suppose we have many copies of an unknown n-qubit state rho. We measure some copies of rho using a known two-outcome measurement E_1, then other copies using a measurement E_2, and so on.
Wednesday, June 6, 2018 3:30 PM EDT
Title: All Graphs are Beautiful
| Speaker: | Alan Arroyo |
| Affiliation: | University of Waterloo |
| Room: | MC 5417 |
Abstract: In this talk I will show that all graphs are beautiful. The proof is by induction on g
Tuesday, June 5, 2018 1:00 PM EDT
Title: On isogeny graphs of supersingular elliptic curves over finite fields
| Speaker: | Gora Adj |
| Affiliation: | University of Waterloo |
| Room: | MC 6486 |
Abstract: In this talk we will present some results on the isogeny graphs of supersingular elliptic curves
Friday, June 1, 2018 3:30 PM EDT
Title: Parameterized Approximation Algorithms for Steiner Network Problems
| Speaker: | Andreas Feldmann |
| Affiliation: | Charles University, Prague, Czech Republic |
| Room: | MC 5501 |
Abstract:
Two standard approaches to handle NP-hard optimization problems are to develop approximation and parameterized algorithms.
Thursday, May 31, 2018 3:30 PM EDT
Title: Counting biased cliques
| Speaker: | Peter Nelson |
| Affiliation: | University of Waterloo |
| Room: | MC 5479 |
Abstract: A biased graph is a pair consisting of an undirected graph G,
Thursday, May 31, 2018 11:30 AM EDT
Title: A single pass bijection between certain quarter plane lattice walks and certain Motzkin-like paths.
| Speaker: | Karen Yeats |
| Affiliation: | University of Waterloo |
| Room: | MC 6486 |
Abstract: A p-tandem quarter plane walk is a walk starting at the origin and remaining in the first quadrant
Friday, May 25, 2018 3:30 PM EDT
Title: Combinatorics in Particle Interactions
| Speaker: | Freddy Cachazo |
| Affiliation: | Perimeter Institute |
| Room: | MC 5501 |
Abstract:
The main approach for testing physical theories of particles is via scattering experiments. The traditional approach for computing theoretical predictions uses Feynman diagrams.
Friday, May 25, 2018 9:00 AM EDT
Title: Miniconference on combinatorial structures in perturbative QFT 2: transforms and graph counting
| Speakers: |
various |
Thursday, May 24, 2018 3:30 PM EDT
Title: Finding Independent Transversals Efficiently
| Speaker: | Alessandra Graf |
| Affiliation: | University of Waterloo |
| Room: | MC 5479 |
Abstract: Let G be a graph whose vertex set is partitioned into classes V1,..., Vm. An independent transversal of G with respect to (V1,...,Vm) is an independent set {v1,...,vm} in G such that vi is in Vi for each i.
Thursday, May 24, 2018 1:30 PM EDT
Title: Graph Reconstruction
| Speaker: | Cathy Wang |
| Affiliation: | University of Waterloo |
| Room: | MC 6486 |
Abstract: The graph reconstruction conjecture by Kelly and Ulam states that all graphs on at least three vertices are determined by their one-vertex deleted subgraphs, up to isomorphism.
Thursday, May 24, 2018 11:30 AM EDT
Title: Asymptotics of the principal of specializations of Schubert polynomials
| Speaker: | Alejandro Morales |
| Affiliation: | University of Massachusetts Amherst |
| Room: | MC 6486 |
Abstract: Schubert polynomials were introduced by Lascoux and Sch\"utzenberger in 1982 to study Schubert varieties.
Friday, May 18, 2018 3:30 PM EDT
Title: The number theory of equiangular lines
| Speaker: | Jon Yard |
| Affiliation: | University of Waterloo |
| Room: | MC 5501 |
Abstract:
It is easy to prove that there can exist at most d2 equiangular complex lines in Cd. Configurations saturating this bound are known by other names: maximal equiangular tight frames, minimal complex projective 2-designs and symmetric informationally complete positive operator-valued measures (SIC-POVMs).
Thursday, May 17, 2018 3:30 PM EDT
Title: Representability of Matroids
| Speaker: | Rutger Campbell |
| Affiliation: | University of Waterloo |
| Room: | MC 5479 |
Abstract: I will go over some negative results regarding characterizations for the class of representable