Past Events

Low Mach number equation sets approximate the equations of motion of a compressible fluid by filtering out the sound waves, which allows the system to evolve on the advective rather than the acoustic time scale. Depending on the degree of...

A random nxm matrix gives a random linear transformation from \Z^m to \Z^n (between vectors with integral coordinates). Asking for the probability that such a map is injective is a question of the non-vanishing of determinants. In this talk, we...

Chase-escape is a competitive growth process in which red particles spread to adjacent uncoloured sites while blue particles overtake and kill adjacent red particles. We can think of this model as prey escaping from pursuing predators. If the red...

I will discuss how to see symmetries of an alternating knot from any reduced alternating diagram. As a consequence we will see that the quotient of an alternating periodic knot is alternating, and that any alternating knot which is p and q periodic...

Reptiles have the ability to replace their teeth continuously throughout life. Replacement occurs in highly patterned waves passing from the back to the front of the mouth, in alternating tooth positions. Although this pattern has been recognized for...

Bertrand's postulate states that there is always a prime in the interval [x,2x] for any x≥1. Applying the prime number theorem, one may further show that there is approximately ∫2xxdtlogt primes in [x,2x] for sufficiently large x. There is a more...

Could an asteroid that explodes over the ocean generate a tsunami threatening coastal populations far away? We show simulations of tsunami propagation from asteroid-generated airbursts. We then present a 1D model with an explicit solution to better...

A key question in population biology is understanding the conditions under which the species of an ecosystem persist or go extinct. Theoretical and empirical studies have shown that persistence can be facilitated or negated by both biotic...

In Section 11.5 of their book, Freedman and Quinn showed that an aspherical 4-manifold M with polycyclic fundamental group pi is determined by pi and the boundary of M. We revisit this result, with a shift in emphasis. We show that if Mis aspherical...

In this talk, we consider families of finite sets that we call shellable and that have been characterized by Chang and Hirst and Hughes as being the families of sets that admit unique solutions to Hall's matching problem. We prove that shellable...