Friday, September 28, 2018 3:30 PM EDT

Title: The Shapiro-Shapiro Conjecture

Speaker: Kevin Purbhoo
Affiliation: University of Waterloo
Room: MC 5501

Abstract:

Given four lines in 3-space, can you find a fifth line that intersects the other four? How many?

This is the smallest non-trivial example of a "Schubert problem". The answer, in this case, is not hard to compute: there are two such lines. Generalizations of this fact date back to 19th century work of Schubert.

Thursday, September 27, 2018 3:30 PM EDT

Title: A characterization of (p,q)-mixing when p/q < 4

Speaker: Ben Moore
Affiliation: University of Waterloo
Room: MC 5417

Abstract: Let Hom(G,H) be the graph whose vertex set is the set of H-colourings of G, and two H-colourings f and g are adjacent if f differs from g in at most one vertex.

Thursday, September 20, 2018 3:30 PM EDT

Title: Naji’s characterization of circle graphs

Speaker: Jim Geelen
Affiliation: University of Waterloo
Room: MC 5417

Abstract: A circle graph is the intersection graph of chords of a circle.

Friday, September 14, 2018 3:30 PM EDT

Title: Rapid mixing of Glauber dynamics for colorings below Vigoda’s 11/6 threshold 

Speaker: Michelle Delcourt
Affiliation: University of Waterloo
Room: MC 5501

Abstract:

A well-known conjecture in computer science and statistical physics is that Glauber dynamics on the set of k-colorings of a graph G on n vertices with maximum degree Δ is rapidly mixing for k ≥ Δ+2.

Friday, September 14, 2018 11:30 AM EDT

Title: Science of Security-- Could Such a Thing Exist?

Speaker: Paul van Oorschot
Affiliation: Carelton University
Room: MC 5501

Abstract: Recent years have seen increasing calls to make security research more "scientific". Who can argue with science being desirable?

Thursday, September 13, 2018 3:30 PM EDT

Title: Entropy and enumeration

Speaker: Jorn van der Pol
Affiliation: University of Waterloo
Room: MC 5417

Abstract: The information-theoretic concept of entropy is closely related to enumeration;

Friday, September 7, 2018 3:30 PM EDT

Title: The smallest eigenvalues of Hamming, Johnson and other graphs

Speaker: Sebastian Cioaba
Affiliation: University of Delaware
Room: MC 5501

Abstract:

The smallest eigenvalue of graphs is closely related to other graph parameters such as the independence number, the chromatic number or the max-cut.

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